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  • Performance of delegate and method group

    - by BlueFox
    Hi I was investigating the performance hit of creating Cachedependency objects, so I wrote a very simple test program as follows: using System; using System.Collections.Generic; using System.Diagnostics; using System.Web.Caching; namespace Test { internal class Program { private static readonly string[] keys = new[] {"Abc"}; private static readonly int MaxIteration = 10000000; private static void Main(string[] args) { Debug.Print("first set"); test7(); test6(); test5(); test4(); test3(); test2(); Debug.Print("second set"); test2(); test3(); test4(); test5(); test6(); test7(); } private static void test2() { DateTime start = DateTime.Now; var list = new List<CacheDependency>(); for (int i = 0; i < MaxIteration; i++) { list.Add(new CacheDependency(null, keys)); } Debug.Print("test2 Time: " + (DateTime.Now - start)); } private static void test3() { DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(() => new CacheDependency(null, keys)); } Debug.Print("test3 Time: " + (DateTime.Now - start)); } private static void test4() { var p = new Program(); DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(p.GetDep); } Debug.Print("test4 Time: " + (DateTime.Now - start)); } private static void test5() { var p = new Program(); DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(() => { return p.GetDep(); }); } Debug.Print("test5 Time: " + (DateTime.Now - start)); } private static void test6() { DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(GetDepSatic); } Debug.Print("test6 Time: " + (DateTime.Now - start)); } private static void test7() { DateTime start = DateTime.Now; var list = new List<Func<CacheDependency>>(); for (int i = 0; i < MaxIteration; i++) { list.Add(() => { return GetDepSatic(); }); } Debug.Print("test7 Time: " + (DateTime.Now - start)); } private CacheDependency GetDep() { return new CacheDependency(null, keys); } private static CacheDependency GetDepSatic() { return new CacheDependency(null, keys); } } } But I can't understand why these result looks like this: first set test7 Time: 00:00:00.4840277 test6 Time: 00:00:02.2041261 test5 Time: 00:00:00.1910109 test4 Time: 00:00:03.1401796 test3 Time: 00:00:00.1820105 test2 Time: 00:00:08.5394884 second set test2 Time: 00:00:07.7324423 test3 Time: 00:00:00.1830105 test4 Time: 00:00:02.3561347 test5 Time: 00:00:00.1750100 test6 Time: 00:00:03.2941884 test7 Time: 00:00:00.1850106 In particular: 1. Why is test4 and test6 much slower than their delegate version? I also noticed that Resharper specifically has a comment on the delegate version suggesting change test5 and test7 to "Covert to method group". Which is the same as test4 and test6 but they're actually slower? 2. I don't seem a consistent performance difference when calling test4 and test6, shouldn't static calls to be always faster?

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  • Pointers to Derived Class Objects Losing vfptr

    - by duckworthd
    To begin, I am trying to write a run-of-the-mill, simple Ray Tracer. In my Ray Tracer, I have multiple types of geometries in the world, all derived from a base class called "SceneObject". I've included the header for it here. /** Interface for all objects that will appear in a scene */ class SceneObject { public: mat4 M, M_inv; Color c; SceneObject(); ~SceneObject(); /** The transformation matrix to be applied to all points of this object. Identity leaves the object in world frame. */ void setMatrix(mat4 M); void setMatrix(MatrixStack mStack); void getMatrix(mat4& M); /** The color of the object */ void setColor(Color c); void getColor(Color& c); /** Alter one portion of the color, leaving the rest as they were. */ void setDiffuse(vec3 rgb); void setSpecular(vec3 rgb); void setEmission(vec3 rgb); void setAmbient(vec3 rgb); void setShininess(double s); /** Fills 'inter' with information regarding an intersection between this object and 'ray'. Ray should be in world frame. */ virtual void intersect(Intersection& inter, Ray ray) = 0; /** Returns a copy of this SceneObject */ virtual SceneObject* clone() = 0; /** Print information regarding this SceneObject for debugging */ virtual void print() = 0; }; As you can see, I've included a couple virtual functions to be implemented elsewhere. In this case, I have only two derived class -- Sphere and Triangle, both of which implement the missing member functions. Finally, I have a Parser class, which is full of static methods that do the actual "Ray Tracing" part. Here's a couple snippets for relevant portions void Parser::trace(Camera cam, Scene scene, string outputFile, int maxDepth) { int width = cam.getNumXPixels(); int height = cam.getNumYPixels(); vector<vector<vec3>> colors; colors.clear(); for (int i = 0; i< width; i++) { vector<vec3> ys; for (int j = 0; j<height; j++) { Intersection intrsct; Ray ray; cam.getRay(ray, i, j); vec3 color; printf("Obtaining color for Ray[%d,%d]\n", i,j); getColor(color, scene, ray, maxDepth); ys.push_back(color); } colors.push_back(ys); } printImage(colors, width, height, outputFile); } void Parser::getColor(vec3& color, Scene scene, Ray ray, int numBounces) { Intersection inter; scene.intersect(inter,ray); if(inter.isIntersecting()){ Color c; inter.getColor(c); c.getAmbient(color); } else { color = vec3(0,0,0); } } Right now, I've forgone the true Ray Tracing part and instead simply return the color of the first object hit, if any. As you have no doubt noticed, the only way the computer knows that a ray has intersected an object is through Scene.intersect(), which I also include. void Scene::intersect(Intersection& i, Ray r) { Intersection result; result.setDistance(numeric_limits<double>::infinity()); result.setIsIntersecting(false); double oldDist; result.getDistance(oldDist); /* Cycle through all objects, making result the closest one */ for(int ind=0; ind<objects.size(); ind++){ SceneObject* thisObj = objects[ind]; Intersection betterIntersect; thisObj->intersect(betterIntersect, r); double newDist; betterIntersect.getDistance(newDist); if (newDist < oldDist){ result = betterIntersect; oldDist = newDist; } } i = result; } Alright, now for the problem. I begin by creating a scene and filling it with objects outside of the Parser::trace() method. Now for some odd reason, I cast Ray for i=j=0 and everything works wonderfully. However, by the time the second ray is cast all of the objects stored in my Scene no longer recognize their vfptr's! I stepped through the code with a debugger and found that the information to all the vfptr's are lost somewhere between the end of getColor() and the continuation of the loop. However, if I change the arguments of getColor() to use a Scene& instead of a Scene, then no loss occurs. What crazy voodoo is this?

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  • Cannot understand NullPointerException with custom adapter

    - by ganesh
    hi, I am trying to create a list view which as TextView that can display html content , an WebView and other basic TextViews.I tried to extend SimpleAdapter but i struck with the problem ,I will be glad if someone can point out the mistake i am doing. In onCreate method ArrayList mylist= resultfromXmlparser(); adap = new MyAdapter(TourLandingPage.this, mylist, R.layout.row, new String[] {"Name", "desc","Duration","Price","imgurl"}, new int[] {R.id.productname,R.id.des,R.id.duration,R.id.pricefrom,R.id.photo}); setListAdapter(adap); My custom Adapter looks like this private class MyAdapter extends SimpleAdapter { ArrayList<HashMap<String,String>> elements; Context ctx; public MyAdapter(Context context, ArrayList<HashMap<String,String>> mylist,int textViewResourceId,String[] names,int[] resouceid) { super(context, mylist,textViewResourceId, names,resouceid); this.elements=mylist; this.ctx=context; } @Override public int getCount() { return elements.size(); } @Override public Object getItem(int position) { return elements.get(position); } @Override public long getItemId(int position) { return position; } @Override public View getView(int position, View convertView, ViewGroup parent) { RelativeLayout rowLayout; if (convertView == null) { rowLayout = (RelativeLayout) LayoutInflater.from(ctx).inflate(R.layout.rowfor_tourlist, parent, false); } else { rowLayout = (RelativeLayout) convertView; } TextView in = (TextView)rowLayout.findViewById(R.id.introduction); TextView du = (TextView)rowLayout.findViewById(R.id.duration); TextView pf = (TextView)rowLayout.findViewById(R.id.pricefrom); TextView pn = (TextView)rowLayout.findViewById(R.id.productname); WebView wv=(WebView)rowLayout.findViewById(R.id.photo); in.setText(Html.fromHtml(mylist.get(position).get("desc"))); du.setText(mylist.get(position).get("Duration")); pf.setText(mylist.get(position).get("Price")); pn.setText(mylist.get(position).get("Name")); wv.getSettings().setJavaScriptEnabled(true); wv.loadUrl(mylist.get(position).get("imgurl")); return convertView; } }//class and my row.xml file looks like RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" TextView android:id="@+id/productname" ...... LinearLayout android:layout_width="wrap_content" android:layout_height="60dip" android:layout_margin="5dip" android:layout_below="@id/productname" android:orientation="horizontal" android:id="@+id/lay1" WebView android:id="@+id/photo" .... TextView android:id="@+id/introduction" ...... LinearLayout TextView android:id="@+id/duration" .... TextView android:id="@+id/pricefrom" ..... RelativeLayout The error i was getting was 04-28 19:46:17.749: ERROR/AndroidRuntime(976): Uncaught handler: thread main exiting due to uncaught exception 04-28 19:46:17.769: ERROR/AndroidRuntime(976): java.lang.NullPointerException 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.setupChild(ListView.java:1693) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.makeAndAddView(ListView.java:1671) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.fillDown(ListView.java:637) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.fillFromTop(ListView.java:694) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.ListView.layoutChildren(ListView.java:1521) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.AbsListView.onLayout(AbsListView.java:1113) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.layoutHorizontal(LinearLayout.java:1108) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.onLayout(LinearLayout.java:920) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.onLayout(LinearLayout.java:918) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1119) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.layoutVertical(LinearLayout.java:998) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.LinearLayout.onLayout(LinearLayout.java:918) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.widget.FrameLayout.onLayout(FrameLayout.java:333) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.View.layout(View.java:6831) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.ViewRoot.performTraversals(ViewRoot.java:996) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.view.ViewRoot.handleMessage(ViewRoot.java:1633) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.os.Handler.dispatchMessage(Handler.java:99) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.os.Looper.loop(Looper.java:123) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at android.app.ActivityThread.main(ActivityThread.java:4338) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at java.lang.reflect.Method.invokeNative(Native Method) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at java.lang.reflect.Method.invoke(Method.java:521) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 04-28 19:46:17.769: ERROR/AndroidRuntime(976): at dalvik.system.NativeStart.main(Native Method) 04-28 19:46:17.789: INFO/Process(52): Sending signal. PID: 976 SIG: 3 04-28 19:46:17.799: INFO/dalvikvm(976): threadid=7: reacting to signal 3 04-28 19:46:17.829: INFO/dalvikvm(976): Wrote stack trace to '/data/anr/traces.txt'

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  • Adding two different Objects by overloading operator+ C++

    - by lampshade
    Hello, I've been trying to figure out how to add a private member from Object A, to a private member from Object B. Both Cat and Dog Class's inheriate from the base class Animal. I have a thrid class 'MyClass', that I want to inheriate the private members of the Cat and Dog class. So in MyClass, I have a friend function to overload the + operator. THe friend function is defined as follows: MyClass operator+(const Dog &dObj, const Cat &cObj); I want to access dObj.age and cObj.age within the above function, invoke by this statement in main: mObj = dObj + cObj; Here is the entire source for a complete reference into the class objects: #include <iostream> #include <vld.h> using namespace std; class Animal { public : Animal() {}; virtual void eat() = 0 {}; virtual void walk() = 0 {}; }; class Dog : public Animal { public : Dog(const char * name, const char * gender, int age); Dog() : name(NULL), gender(NULL), age(0) {}; virtual ~Dog(); void eat(); void bark(); void walk(); private : char * name; char * gender; int age; }; class Cat : public Animal { public : Cat(const char * name, const char * gender, int age); Cat() : name(NULL), gender(NULL), age(0) {}; virtual ~Cat(); void eat(); void meow(); void walk(); private : char * name; char * gender; int age; }; class MyClass : private Cat, private Dog { public : MyClass() : action(NULL) {}; void setInstance(Animal &newInstance); void doSomething(); friend MyClass operator+(const Dog &dObj, const Cat &cObj); private : Animal * action; }; Cat::Cat(const char * name, const char * gender, int age) : name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Cat::~Cat() { delete name; delete gender; age = 0; } void Cat::walk() { cout << name << " is walking now.. " << endl; } void Cat::eat() { cout << name << " is eating now.. " << endl; } void Cat::meow() { cout << name << " says meow.. " << endl; } Dog::Dog(const char * name, const char * gender, int age) : name(new char[strlen(name)+1]), gender(new char[strlen(gender)+1]), age(age) { if (name) { size_t length = strlen(name) +1; strcpy_s(this->name, length, name); } else name = NULL; if (gender) { size_t length = strlen(gender) +1; strcpy_s(this->gender, length, gender); } else gender = NULL; if (age) { this->age = age; } } Dog::~Dog() { delete name; delete gender; age = 0; } void Dog::eat() { cout << name << " is eating now.. " << endl; } void Dog::bark() { cout << name << " says woof.. " << endl; } void Dog::walk() { cout << name << " is walking now.." << endl; } void MyClass::setInstance(Animal &newInstance) { action = &newInstance; } void MyClass::doSomething() { action->walk(); action->eat(); } MyClass operator+(const Dog &dObj, const Cat &cObj) { MyClass A; //dObj.age; //cObj.age; return A; } int main() { MyClass mObj; Dog dObj("B", "Male", 4); Cat cObj("C", "Female", 5); mObj.setInstance(dObj); // set the instance specific to the object. mObj.doSomething(); // something happens based on which object is passed in dObj.bark(); mObj.setInstance(cObj); mObj.doSomething(); cObj.meow(); mObj = dObj + cObj; return 0; }

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  • Is there a better way to avoid an infinite loop using winforms?

    - by Hamish Grubijan
    I am using .Net 3.5 for now. Right now I am using a using trick to disable and enable events around certain sections of code. The user can change either days, hours, minutes or total minutes, and that should not cause an infinite cascade of events (e.g. minutes changing total, total changing minutes, etc.) While the code does what I want, there might be a better / more straight-forward way. Do you know of any? For brawny points: This control will be used by multiple teams - I do not want to make it embarrassing. I suspect that I do not need to reinvent the wheel when defining hours in a day, days in week, etc. Some other standard .Net library out there must have it. Any other remarks regarding code? This using (EventHacker.DisableEvents(this)) business - that must be a common pattern in .Net ... changing the setting temporarily. What is the name of it? I'd like to be able to refer to it in a comment and also read up more on current implementations. In the general case not only a handle to the thing being changed needs to be remembered, but also the previous state (in this case previous state does not matter - events are turned on and off unconditionally). Then there is also a possibility of multi-threaded hacking. One could also utilize generics to make the code arguably cleaner. Figuring all this out can lead to a multi-page blog post. I'd be happy to hear some of the answers. P.S. Does it seem like I suffer from obsessive compulsive disorder? Some people like to get things finished and move on; I like to keep them open ... there is always a better way. // Corresponding Designer class is omitted. using System; using System.Windows.Forms; namespace XYZ // Real name masked { interface IEventHackable { void EnableEvents(); void DisableEvents(); } public partial class PollingIntervalGroupBox : GroupBox, IEventHackable { private const int DAYS_IN_WEEK = 7; private const int MINUTES_IN_HOUR = 60; private const int HOURS_IN_DAY = 24; private const int MINUTES_IN_DAY = MINUTES_IN_HOUR * HOURS_IN_DAY; private const int MAX_TOTAL_DAYS = 100; private static readonly decimal MIN_TOTAL_NUM_MINUTES = 1; // Anything faster than once per minute can bog down our servers. private static readonly decimal MAX_TOTAL_NUM_MINUTES = (MAX_TOTAL_DAYS * MINUTES_IN_DAY) - 1; // 99 days should be plenty. // The value above was chosen so to not cause an overflow exception. // Watch out for it - numericUpDownControls each have a MaximumValue setting. public PollingIntervalGroupBox() { InitializeComponent(); InitializeComponentCustom(); } private void InitializeComponentCustom() { this.m_upDownDays.Maximum = MAX_TOTAL_DAYS - 1; this.m_upDownHours.Maximum = HOURS_IN_DAY - 1; this.m_upDownMinutes.Maximum = MINUTES_IN_HOUR - 1; this.m_upDownTotalMinutes.Maximum = MAX_TOTAL_NUM_MINUTES; this.m_upDownTotalMinutes.Minimum = MIN_TOTAL_NUM_MINUTES; } private void m_upDownTotalMinutes_ValueChanged(object sender, EventArgs e) { setTotalMinutes(this.m_upDownTotalMinutes.Value); } private void m_upDownDays_ValueChanged(object sender, EventArgs e) { updateTotalMinutes(); } private void m_upDownHours_ValueChanged(object sender, EventArgs e) { updateTotalMinutes(); } private void m_upDownMinutes_ValueChanged(object sender, EventArgs e) { updateTotalMinutes(); } private void updateTotalMinutes() { this.setTotalMinutes( MINUTES_IN_DAY * m_upDownDays.Value + MINUTES_IN_HOUR * m_upDownHours.Value + m_upDownMinutes.Value); } public decimal TotalMinutes { get { return m_upDownTotalMinutes.Value; } set { m_upDownTotalMinutes.Value = value; } } public decimal TotalHours { set { setTotalMinutes(value * MINUTES_IN_HOUR); } } public decimal TotalDays { set { setTotalMinutes(value * MINUTES_IN_DAY); } } public decimal TotalWeeks { set { setTotalMinutes(value * DAYS_IN_WEEK * MINUTES_IN_DAY); } } private void setTotalMinutes(decimal nTotalMinutes) { if (nTotalMinutes < MIN_TOTAL_NUM_MINUTES) { setTotalMinutes(MIN_TOTAL_NUM_MINUTES); return; // Must be carefull with recursion. } if (nTotalMinutes > MAX_TOTAL_NUM_MINUTES) { setTotalMinutes(MAX_TOTAL_NUM_MINUTES); return; // Must be carefull with recursion. } using (EventHacker.DisableEvents(this)) { // First set the total minutes this.m_upDownTotalMinutes.Value = nTotalMinutes; // Then set the rest this.m_upDownDays.Value = (int)(nTotalMinutes / MINUTES_IN_DAY); nTotalMinutes = nTotalMinutes % MINUTES_IN_DAY; // variable reuse. this.m_upDownHours.Value = (int)(nTotalMinutes / MINUTES_IN_HOUR); nTotalMinutes = nTotalMinutes % MINUTES_IN_HOUR; this.m_upDownMinutes.Value = nTotalMinutes; } } // Event magic public void EnableEvents() { this.m_upDownTotalMinutes.ValueChanged += this.m_upDownTotalMinutes_ValueChanged; this.m_upDownDays.ValueChanged += this.m_upDownDays_ValueChanged; this.m_upDownHours.ValueChanged += this.m_upDownHours_ValueChanged; this.m_upDownMinutes.ValueChanged += this.m_upDownMinutes_ValueChanged; } public void DisableEvents() { this.m_upDownTotalMinutes.ValueChanged -= this.m_upDownTotalMinutes_ValueChanged; this.m_upDownDays.ValueChanged -= this.m_upDownDays_ValueChanged; this.m_upDownHours.ValueChanged -= this.m_upDownHours_ValueChanged; this.m_upDownMinutes.ValueChanged -= this.m_upDownMinutes_ValueChanged; } // We give as little info as possible to the 'hacker'. private sealed class EventHacker : IDisposable { IEventHackable _hackableHandle; public static IDisposable DisableEvents(IEventHackable hackableHandle) { return new EventHacker(hackableHandle); } public EventHacker(IEventHackable hackableHandle) { this._hackableHandle = hackableHandle; this._hackableHandle.DisableEvents(); } public void Dispose() { this._hackableHandle.EnableEvents(); } } } }

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  • ArrayList access

    - by Ricky McQuesten
    So once again I have a question about this program. I want to store transactions that are made in an arraylist and then have an option in the case menu where I can print out those that are stored. I have been researching online and have been unable to find a solution to this, so is this possible and how would I go about doing this? I also want to attach a timestamp to each transaction as well. Here is the code I have so far. So my question is how would I add a timestamp to each withdrawal or deposit, and how would I store each transaction in array list? import java.util.*; public class BankAccount extends Money { //inheritence static String name; public static int acctNum; public static double balance, amount; BankAccount(String name, int accNo, double bal) { this.name = name; this.acctNum = accNo; this.balance = bal; } void display() { System.out.println("Your Name:" + name); System.out.println("Your Account Number:" + acctNum); System.out.println("Your Current Account Balance:" + Money.getBalance()); } void displayBalance() { System.out.println("Balance:" + balance); } } import java.util.Scanner; /** * * @author Ricky */ public class Money { public static int accountNumber; public static double balance; static double amount; static String name; public void setDeposit(double amount) { balance = balance + amount; if (amount < 0) { System.out.println("Invalid"); } } public double getDeposit() { return 1; } public void setBalance(double b) { balance = b; } public static double getBalance() { return balance; } public void setWithdraw(double amount) { if (balance < amount) { System.out.println("Not enough funds."); } else if(amount < 0) { System.out.println("Invalid"); } else { balance = balance - amount; } } public double getWithdraw() { return 1; } } import java.util.*; public class Client { public static void main(String args[]) { int n = 0; int count; String trans; ArrayList<String> transaction= new ArrayList<String>(n); Scanner input = new Scanner(System.in); System.out.println("Welcome to First National Bank"); System.out.println("Please enter your name: "); String cusName = input.nextLine(); System.out.println("You will now be assigned an account number."); Random randomGenerator = new Random(); int accNo = randomGenerator.nextInt(100000); //random number System.out.println("Your account number is: " + accNo); System.out.println("Please enter your initial account balance: "); Double balance = input.nextDouble(); BankAccount b1 = new BankAccount(cusName, accNo, balance); b1.setBalance(balance); int menu; /*System.out.println("Menu"); System.out.println("1. Deposit Amount"); System.out.println("2. Withdraw Amount"); System.out.println("3. Display Information"); System.out.println("4. Exit");*/ boolean quit = false; do { System.out.println("*******Menu*******"); System.out.println("1. Deposit Amount"); // menu to take input from user System.out.println("2. Withdraw Amount"); System.out.println("3. Display Information"); System.out.println("4. Exit"); System.out.print("Please enter your choice: "); menu = input.nextInt(); switch (menu) { case 1: System.out.print("Enter depost amount:"); b1.setDeposit(input.nextDouble()); b1.getDeposit(); transaction.add(trans); break; case 2: System.out.println("Current Account Balance=" + b1.getBalance()); System.out.print("Enter withdrawal amount:"); b1.setWithdraw(input.nextDouble()); b1.getWithdraw(); transaction.add(trans); break; // switch statments to do a loop case 3: b1.display(); break; case 4: quit = true; break; } } while (!quit); } } public class Date { static Date time = new Date(); }

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  • C -Segmentation fault after the 4th call of the function!

    - by FILIaS
    It seems at least weird to me... The program runs normally.But after I call the enter() function for the 4th time,there is a segmentation fault!I would appreciate any help. With the following function enter() I wanna add user commands' datas to a list. [Some part of the code is already posted on another question of me, but I think I should post it again...as it's a different problem I'm facing now.] /* struct for all the datas that user enters on file*/ typedef struct catalog { char short_name[50]; char surname[50]; signed int amount; char description[1000]; struct catalog *next; }catalog,*catalogPointer; catalogPointer current; catalogPointer head = NULL; void enter(void) //user command: i <name> <surname> <amount> <description> { int n,j=2,k=0; char temp[1500]; char *short_name,*surname,*description; signed int amount; char* params = strchr(command,' ') + 1; //strchr returns a pointer to the 1st space on the command.U want a pointer to the char right after that space. strcpy(temp, params); //params is saved as temp. char *curToken = strtok(temp," "); //strtok cuts 'temp' into strings between the spaces and saves them to 'curToken' printf("temp is:%s \n",temp); printf("\nWhat you entered for saving:\n"); for (n = 0; curToken; ++n) //until curToken ends: { if (curToken) { short_name = malloc(strlen(curToken) + 1); strncpy(short_name, curToken, sizeof (short_name)); } printf("Short Name: %s \n",short_name); curToken = strtok(NULL," "); if (curToken) { surname = malloc(strlen(curToken) + 1); strncpy(surname, curToken,sizeof (surname)); } printf("SurName: %s \n",surname); curToken = strtok(NULL," "); if (curToken) { //int * amount= malloc(sizeof (signed int *)); char *chk; amount = (int) strtol(curToken, &chk, 10); if (!isspace(*chk) && *chk != 0) fprintf(stderr,"Warning: expected integer value for amount, received %s instead\n",curToken); } printf("Amount: %d \n",amount); curToken = strtok(NULL,"\0"); if (curToken) { description = malloc(strlen(curToken) + 1); strncpy(description, curToken, sizeof (description)); } printf("Description: %s \n",description); break; } if (findEntryExists(head, surname,short_name) != NULL) //call function in order to see if entry exists already on the catalog printf("\nAn entry for <%s %s> is already in the catalog!\nNew entry not entered.\n",short_name,surname); else { printf("\nTry to entry <%s %s %d %s> in the catalog list!\n",short_name,surname,amount,description); newEntry(&head,short_name,surname,amount,description); printf("\n**Entry done!**\n"); } // Maintain the list in alphabetical order by surname. } catalogPointer findEntryExists (catalogPointer head, char num[],char first[]) { catalogPointer p = head; while (p != NULL && strcmp(p->surname, num) != 0 && strcmp(p->short_name,first) != 0) { p = p->next; } return p; } catalogPointer newEntry (catalog** headRef,char short_name[], char surname[], signed int amount, char description[]) { catalogPointer newNode = (catalogPointer)malloc(sizeof(catalog)); catalogPointer first; catalogPointer second; catalogPointer tmp; first=head; second=NULL; strcpy(newNode->short_name, short_name); strcpy(newNode->surname, surname); newNode->amount=amount; strcpy(newNode->description, description); //SEGMENTATION ON THE 4TH RUN OF PROGRAM STOPS HERE depending on the names each time it gets! while (first!=NULL) { if (strcmp(surname,first->surname)>0) second=first; else if (strcmp(surname,first->surname)==0) { if (strcmp(short_name,first->short_name)>0) second=first; } first=first->next; } if (second==NULL) { newNode->next=head; head=newNode; } else { tmp=second->next; newNode->next=tmp; first->next=newNode; } }

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  • Collections not read from hibernate/ehcache second-level-cache

    - by Mark van Venrooij
    I'm trying to cache lazy loaded collections with ehcache/hibernate in a Spring project. When I execute a session.get(Parent.class, 123) and browse through the children multiple times a query is executed every time to fetch the children. The parent is only queried the first time and then resolved from the cache. Probably I'm missing something, but I can't find the solution. Please see the relevant code below. I'm using Spring (3.2.4.RELEASE) Hibernate(4.2.1.Final) and ehcache(2.6.6) The parent class: @Entity @Table(name = "PARENT") @Cacheable @Cache(usage = CacheConcurrencyStrategy.READ_WRITE, include = "all") public class ServiceSubscriptionGroup implements Serializable { /** The Id. */ @Id @Column(name = "ID") private int id; @OneToMany(fetch = FetchType.LAZY, mappedBy = "parent") @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) private List<Child> children; public List<Child> getChildren() { return children; } public void setChildren(List<Child> children) { this.children = children; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Parent that = (Parent) o; if (id != that.id) return false; return true; } @Override public int hashCode() { return id; } } The child class: @Entity @Table(name = "CHILD") @Cacheable @Cache(usage = CacheConcurrencyStrategy.READ_WRITE, include = "all") public class Child { @Id @Column(name = "ID") private int id; @ManyToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL) @JoinColumn(name = "PARENT_ID") @Cache(usage = CacheConcurrencyStrategy.READ_WRITE) private Parent parent; public int getId() { return id; } public void setId(final int id) { this.id = id; } private Parent getParent(){ return parent; } private void setParent(Parent parent) { this.parent = parent; } @Override public boolean equals(final Object o) { if (this == o) { return true; } if (o == null || getClass() != o.getClass()) { return false; } final Child that = (Child) o; return id == that.id; } @Override public int hashCode() { return id; } } The application context: <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="annotatedClasses"> <list> <value>Parent</value> <value>Child</value> </list> </property> <property name="hibernateProperties"> <props> <prop key="hibernate.dialect">org.hibernate.dialect.SQLServer2008Dialect</prop> <prop key="hibernate.hbm2ddl.auto">validate</prop> <prop key="hibernate.ejb.naming_strategy">org.hibernate.cfg.ImprovedNamingStrategy</prop> <prop key="hibernate.connection.charSet">UTF-8</prop> <prop key="hibernate.show_sql">true</prop> <prop key="hibernate.format_sql">true</prop> <prop key="hibernate.use_sql_comments">true</prop> <!-- cache settings ehcache--> <prop key="hibernate.cache.use_second_level_cache">true</prop> <prop key="hibernate.cache.use_query_cache">true</prop> <prop key="hibernate.cache.region.factory_class"> org.hibernate.cache.ehcache.SingletonEhCacheRegionFactory</prop> <prop key="hibernate.generate_statistics">true</prop> <prop key="hibernate.cache.use_structured_entries">true</prop> <prop key="hibernate.cache.use_query_cache">true</prop> <prop key="hibernate.transaction.factory_class"> org.hibernate.engine.transaction.internal.jta.JtaTransactionFactory</prop> <prop key="hibernate.transaction.jta.platform"> org.hibernate.service.jta.platform.internal.JBossStandAloneJtaPlatform</prop> </props> </property> </bean> The testcase I'm running: @Test public void testGetParentFromCache() { for (int i = 0; i <3 ; i++ ) { getEntity(); } } private void getEntity() { Session sess = sessionFactory.openSession() sess.setCacheMode(CacheMode.NORMAL); Transaction t = sess.beginTransaction(); Parent p = (Parent) s.get(Parent.class, 123); Assert.assertNotNull(p); Assert.assertNotNull(p.getChildren().size()); t.commit(); sess.flush(); sess.clear(); sess.close(); } In the logging I can see that the first time 2 queries are executed getting the parent and getting the children. Furthermore the logging shows that the child entities as well as the collection are stored in the 2nd level cache. However when reading the collection a query is executed to fetch the children on second and third attempt.

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  • JSF2 - use view scope managed bean to pass value between navigation

    - by Fekete Kamosh
    Hi all, I am solving how to pass values from one page to another without making use of session scope managed bean. For most managed beans I would like to have only Request scope. I created a very, very simple calculator example which passes Result object resulting from actions on request bean (CalculatorRequestBean) from 5th phase as initializing value for new instance of request bean initialized in next phase lifecycle. In fact - in production environment we need to pass much more complicated data object which is not as primitive as Result defined below. What is your opinion on this solution which considers both possibilities - we stay on the same view or we navigate to the new one. But in both cases I can get to previous value stored passed using view scoped managed bean. Calculator page: <?xml version='1.0' encoding='UTF-8' ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xmlns:h="http://java.sun.com/jsf/html"> <h:head> <title>Calculator</title> </h:head> <h:body> <h:form> <h:panelGrid columns="2"> <h:outputText value="Value to use:"/> <h:inputText value="#{calculatorBeanRequest.valueToAdd}"/> <h:outputText value="Navigate to new view:"/> <h:selectBooleanCheckbox value="#{calculatorBeanRequest.navigateToNewView}"/> <h:commandButton value="Add" action="#{calculatorBeanRequest.add}"/> <h:commandButton value="Subtract" action="#{calculatorBeanRequest.subtract}"/> <h:outputText value="Result:"/> <h:outputText value="#{calculatorBeanRequest.result.value}"/> <h:outputText value="DUMMY" rendered="#{resultBeanView.dummy}"/> </h:panelGrid> </h:form> </h:body> Object to be passed through lifecycle: package cz.test.calculator; import java.io.Serializable; /** * Data object passed among pages. * Lets imagine it holds something much more complicated than primitive int */ public class Result implements Serializable { private int value; public void setValue(int value) { this.value = value; } public int getValue() { return value; } } Request scoped managed bean used on view "calculator.xhtml" package cz.test.calculator; import javax.annotation.PostConstruct; import javax.faces.bean.ManagedBean; import javax.faces.bean.ManagedProperty; import javax.faces.bean.RequestScoped; @ManagedBean @RequestScoped public class CalculatorBeanRequest { @ManagedProperty(value="#{resultBeanView}") ResultBeanView resultBeanView; private Result result; private int valueToAdd; /** * Should perform navigation to */ private boolean navigateToNewView; /** Creates a new instance of CalculatorBeanRequest */ public CalculatorBeanRequest() { } @PostConstruct public void init() { // Remember already saved result from view scoped bean result = resultBeanView.getResult(); } // Dependency injections public void setResultBeanView(ResultBeanView resultBeanView) { this.resultBeanView = resultBeanView; } public ResultBeanView getResultBeanView() { return resultBeanView; } // Getters, setter public void setValueToAdd(int valueToAdd) { this.valueToAdd = valueToAdd; } public int getValueToAdd() { return valueToAdd; } public boolean isNavigateToNewView() { return navigateToNewView; } public void setNavigateToNewView(boolean navigateToNewView) { this.navigateToNewView = navigateToNewView; } public Result getResult() { return result; } // Actions public String add() { result.setValue(result.getValue() + valueToAdd); return isNavigateToNewView() ? "calculator" : null; } public String subtract() { result.setValue(result.getValue() - valueToAdd); return isNavigateToNewView() ? "calculator" : null; } } and finally view scoped managed bean to pass Result variable to new page: package cz.test.calculator; import java.io.Serializable; import javax.annotation.PostConstruct; import javax.faces.bean.ManagedBean; import javax.faces.bean.ViewScoped; import javax.faces.context.FacesContext; @ManagedBean @ViewScoped public class ResultBeanView implements Serializable { private Result result = new Result(); /** Creates a new instance of ResultBeanView */ public ResultBeanView() { } @PostConstruct public void init() { // Try to find request bean ManagedBeanRequest and reset result value CalculatorBeanRequest calculatorBeanRequest = (CalculatorBeanRequest)FacesContext.getCurrentInstance().getExternalContext().getRequestMap().get("calculatorBeanRequest"); if(calculatorBeanRequest != null) { setResult(calculatorBeanRequest.getResult()); } } /** No need to have public modifier as not used on view * but only in managed bean within the same package */ void setResult(Result result) { this.result = result; } /** No need to have public modifier as not used on view * but only in managed bean within the same package */ Result getResult() { return result; } /** * To be called on page to instantiate ResultBeanView in Render view phase */ public boolean isDummy() { return false; } }

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  • How would you go about tackling this problem? [SOLVED in C++]

    - by incrediman
    Intro: EDIT: See solution at the bottom of this question (c++) I have a programming contest coming up in about half a week, and I've been prepping :) I found a bunch of questions from this canadian competition, they're great practice: http://cemc.math.uwaterloo.ca/contests/computing/2009/stage2/day1.pdf I'm looking at problem B ("Dinner"). Any idea where to start? I can't really think of anything besides the naive approach (ie. trying all permutations) which would take too long to be a valid answer. Btw, the language there says c++ and pascal I think, but i don't care what language you use - I mean really all I want is a hint as to the direction I should proceed in, and perhpas a short explanation to go along with it. It feels like I'm missing something obvious... Of course extended speculation is more than welcome, but I just wanted to clarify that I'm not looking for a full solution here :) Short version of the question: You have a binary string N of length 1-100 (in the question they use H's and G's instead of one's and 0's). You must remove all of the digits from it, in the least number of steps possible. In each step you may remove any number of adjacent digits so long as they are the same. That is, in each step you can remove any number of adjacent G's, or any number of adjacent H's, but you can't remove H's and G's in one step. Example: HHHGHHGHH Solution to the example: 1. HHGGHH (remove middle Hs) 2. HHHH (remove middle Gs) 3. Done (remove Hs) -->Would return '3' as the answer. Note that there can also be a limit placed on how large adjacent groups have to be when you remove them. For example it might say '2', and then you can't remove single digits (you'd have to remove pairs or larger groups at a time). Solution I took Mark Harrison's main algorithm, and Paradigm's grouping idea and used them to create the solution below. You can try it out on the official test cases if you want. //B.cpp //include debug messages? #define DEBUG false #include <iostream> #include <stdio.h> #include <vector> using namespace std; #define FOR(i,n) for (int i=0;i<n;i++) #define FROM(i,s,n) for (int i=s;i<n;i++) #define H 'H' #define G 'G' class String{ public: int num; char type; String(){ type=H; num=0; } String(char type){ this->type=type; num=1; } }; //n is the number of bits originally in the line //k is the minimum number of people you can remove at a time //moves is the counter used to determine how many moves we've made so far int n, k, moves; int main(){ /*Input from File*/ scanf("%d %d",&n,&k); char * buffer = new char[200]; scanf("%s",buffer); /*Process input into a vector*/ //the 'line' is a vector of 'String's (essentially contigious groups of identical 'bits') vector<String> line; line.push_back(String()); FOR(i,n){ //if the last String is of the correct type, simply increment its count if (line.back().type==buffer[i]) line.back().num++; //if the last String is of the wrong type but has a 0 count, correct its type and set its count to 1 else if (line.back().num==0){ line.back().type=buffer[i]; line.back().num=1; } //otherwise this is the beginning of a new group, so create the new group at the back with the correct type, and a count of 1 else{ line.push_back(String(buffer[i])); } } /*Geedily remove groups until there are at most two groups left*/ moves=0; int I;//the position of the best group to remove int bestNum;//the size of the newly connected group the removal of group I will create while (line.size()>2){ /*START DEBUG*/ if (DEBUG){ cout<<"\n"<<moves<<"\n----\n"; FOR(i,line.size()) printf("%d %c \n",line[i].num,line[i].type); cout<<"----\n"; } /*END DEBUG*/ I=1; bestNum=-1; FROM(i,1,line.size()-1){ if (line[i-1].num+line[i+1].num>bestNum && line[i].num>=k){ bestNum=line[i-1].num+line[i+1].num; I=i; } } //remove the chosen group, thus merging the two adjacent groups line[I-1].num+=line[I+1].num; line.erase(line.begin()+I);line.erase(line.begin()+I); moves++; } /*START DEBUG*/ if (DEBUG){ cout<<"\n"<<moves<<"\n----\n"; FOR(i,line.size()) printf("%d %c \n",line[i].num,line[i].type); cout<<"----\n"; cout<<"\n\nFinal Answer: "; } /*END DEBUG*/ /*Attempt the removal of the last two groups, and output the final result*/ if (line.size()==2 && line[0].num>=k && line[1].num>=k) cout<<moves+2;//success else if (line.size()==1 && line[0].num>=k) cout<<moves+1;//success else cout<<-1;//not everyone could dine. /*START DEBUG*/ if (DEBUG){ cout<<" moves."; } /*END DEBUG*/ }

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  • how to use Thread in java ?

    - by tiendv
    Hi all i have code use googleseach API I want to use Thread to improve speed of my program. But i have a problem here is code import java.io.BufferedReader; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.InputStreamReader; import java.net.URL; import java.net.URLConnection; import java.net.URLEncoder; import java.util.ArrayList; import java.util.Enumeration; import java.util.Hashtable; import java.util.List; import org.json.JSONArray; import org.json.JSONObject; import com.yahoo.search.WebSearchResult; /** * Simple Search using Google ajax Web Services * * @author Daniel Jones Copyright 2006 Daniel Jones Licensed under BSD open * source license http://www.opensource.org/licenses/bsd-license.php */ public class GoogleSearchEngine extends Thread { private String queryString; private int maxResult; private ArrayList<String> resultGoogleArrayList = null; public ArrayList<String> getResultGoogleArrayList() { return resultGoogleArrayList; } public void setResultGoogleArrayList(ArrayList<String> resultGoogleArrayList) { this.resultGoogleArrayList = resultGoogleArrayList; } public String getQueryString() { return queryString; } public void setQueryString(String queryString) { this.queryString = queryString; } public int getMaxResult() { return maxResult; } public void setMaxResult(int maxResult) { this.maxResult = maxResult; } // Put your website here public final static String HTTP_REFERER = "http://www.example.com/"; public static ArrayList<String> makeQuery(String query, int maxResult) { ArrayList<String> finalArray = new ArrayList<String>(); ArrayList<String> returnArray = new ArrayList<String>(); try { query = URLEncoder.encode(query, "UTF-8"); int i = 0; String line = ""; StringBuilder builder = new StringBuilder(); while (true) { // Call GoogleAjaxAPI to submit the query URL url = new URL("http://ajax.googleapis.com/ajax/services/search/web?start=" + i + "&rsz=large&v=1.0&q=" + query); URLConnection connection = url.openConnection(); if (connection == null) { break; } // Value i to stop while or Max result if (i >= maxResult) { break; } connection.addRequestProperty("Referer", HTTP_REFERER); BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream(),"utf-8")); while ((line = reader.readLine()) != null) { builder.append(line); } String response = builder.toString(); JSONObject json = new JSONObject(response); JSONArray ja = json.getJSONObject("responseData").getJSONArray("results"); for (int j = 0; j < ja.length(); j++) { try { JSONObject k = ja.getJSONObject(j); // Break string into 2 parts: URL and Title by <br> returnArray.add(k.getString("url") + "<br>" + k.getString("titleNoFormatting")); } catch (Exception e) { e.printStackTrace(); } } i += 8; } // Remove objects that is over the max number result required if (returnArray.size() > maxResult) { for (int k=0; k<maxResult; k++){ finalArray.add(returnArray.get(k)); } } else return returnArray; return finalArray; } catch (Exception e) { e.printStackTrace(); } return null; } @Override public void run() { // TODO Auto-generated method stub //super.run(); this.resultGoogleArrayList = GoogleSearchEngine.makeQuery(queryString, maxResult); System.out.println("Code run here "); } public static void main(String[] args) { Thread test = new GoogleSearchEngine(); ((GoogleSearchEngine) test).setQueryString("data "); ((GoogleSearchEngine) test).setMaxResult(10); test.start(); ArrayList<String> returnGoogleArrayList = null; returnGoogleArrayList = ((GoogleSearchEngine) test).getResultGoogleArrayList(); System.out.print("contents of al:" + returnGoogleArrayList); } } when i run it, it can run into run method but it don't excute make query methor and return null array. when i do't use Thread it can nomal . Can you give me the reason why ? or give a sulution Thanks

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  • OpenGL true coordinates and glutTimerFunc() problem C++

    - by Meko
    HI I am starting to learn openGl for C++.but at stating point I stucked. I have 2 question that is the coordinates for drawing some objects? I mean where is X, Y and Z? Second one I am making tutorial from some sites. and I am trying to animate my triangle.In tutorial it works but on my computer not.I Also downloaded source codes but It doesnt move. Here sample codes. I thougt that problem is glutTimerFunc(). #include #include #ifdef APPLE #include #include #else #include #endif using namespace std; //Called when a key is pressed void handleKeypress(unsigned char key, int x, int y) { switch (key) { case 27: //Escape key exit(0); } } //Initializes 3D rendering void initRendering() { glEnable(GL_DEPTH_TEST); } //Called when the window is resized void handleResize(int w, int h) { glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, (double)w / (double)h, 1.0, 200.0); } float _angle = 30.0f; float _cameraAngle = 0.0f; //Draws the 3D scene void drawScene() { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); //Switch to the drawing perspective glLoadIdentity(); //Reset the drawing perspective glRotatef(-_cameraAngle, 0.0f, 1.0f, 0.0f); //Rotate the camera glTranslatef(0.0f, 0.0f, -5.0f); //Move forward 5 units glPushMatrix(); //Save the transformations performed thus far glTranslatef(0.0f, -1.0f, 0.0f); //Move to the center of the trapezoid glRotatef(_angle, 0.0f, 0.0f, 1.0f); //Rotate about the z-axis glBegin(GL_QUADS); //Trapezoid glVertex3f(-0.7f, -0.5f, 0.0f); glVertex3f(0.7f, -0.5f, 0.0f); glVertex3f(0.4f, 0.5f, 0.0f); glVertex3f(-0.4f, 0.5f, 0.0f); glEnd(); glPopMatrix(); //Undo the move to the center of the trapezoid glPushMatrix(); //Save the current state of transformations glTranslatef(1.0f, 1.0f, 0.0f); //Move to the center of the pentagon glRotatef(_angle, 0.0f, 1.0f, 0.0f); //Rotate about the y-axis glScalef(0.7f, 0.7f, 0.7f); //Scale by 0.7 in the x, y, and z directions glBegin(GL_TRIANGLES); //Pentagon glVertex3f(-0.5f, -0.5f, 0.0f); glVertex3f(0.5f, -0.5f, 0.0f); glVertex3f(-0.5f, 0.0f, 0.0f); glVertex3f(-0.5f, 0.0f, 0.0f); glVertex3f(0.5f, -0.5f, 0.0f); glVertex3f(0.5f, 0.0f, 0.0f); glVertex3f(-0.5f, 0.0f, 0.0f); glVertex3f(0.5f, 0.0f, 0.0f); glVertex3f(0.0f, 0.5f, 0.0f); glEnd(); glPopMatrix(); //Undo the move to the center of the pentagon glPushMatrix(); //Save the current state of transformations glTranslatef(-1.0f, 1.0f, 0.0f); //Move to the center of the triangle glRotatef(_angle, 1.0f, 2.0f, 3.0f); //Rotate about the the vector (1, 2, 3) glBegin(GL_TRIANGLES); //Triangle glVertex3f(0.5f, -0.5f, 0.0f); glVertex3f(0.0f, 0.5f, 0.0f); glVertex3f(-0.5f, -0.5f, 0.0f); glEnd(); glPopMatrix(); //Undo the move to the center of the triangle glutSwapBuffers(); } void update(int value) { _angle += 2.0f; if (_angle 360) { _angle -= 260; } glutPostRedisplay(); //Tell GLUT that the display has changed //Tell GLUT to call update again in 25 milliseconds glutTimerFunc(25, update, 0); } int main(int argc, char** argv) { //Initialize GLUT glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH); glutInitWindowSize(400, 400); //Create the window glutCreateWindow("Transformations and Timers - videotutorialsrock.com"); initRendering(); //Set handler functions glutDisplayFunc(drawScene); glutKeyboardFunc(handleKeypress); glutReshapeFunc(handleResize); glutTimerFunc(24, update, 0); //Add a timer glutMainLoop(); return 0; }

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  • How to make code run a certain amount of times before returning something?

    - by user3564967
    I made a trivia game and I have to make a method (SuccessOrFail) that will return whether the user beat the trivia or not. namespace D4 { /// <summary> /// Displays the trivia and returns whether the user succeeded or not, number of questions asked, and a free piece of trivia. /// </summary> public partial class TriviaForm : Form { private Trivia trivia; private Question question; private Random rand = new Random(); private HashSet<int> pickedQuestion = new HashSet<int>(); private string usersAnswer; private int numCorrectAnswers; private int numIncorrectAnswers; public TriviaForm() { InitializeComponent(); this.trivia = new Trivia(); QuestionRandomizer(); QuestionOutputter(); } /// <summary> /// This method will return true if succeeded or false if not. /// </summary> /// <returns>Whether the user got the trivia right or not</returns> public bool SuccessOrFail(bool wumpus) { bool successOrFail = false; int maxQuestions = 3; if (wumpus == true) maxQuestions = 5; int numNeededCorrect = maxQuestions / 2 + 1; if (this.usersAnswer == question.CorrectAnswer.ToString()) numCorrectAnswers++; else numIncorrectAnswers++; if (numCorrectAnswers + numIncorrectAnswers == maxQuestions) { if (numCorrectAnswers == numNeededCorrect) successOrFail = true; else successOrFail = false; numCorrectAnswers = 0; numIncorrectAnswers = 0; return successOrFail; } else return false; } /// <summary> /// This method will output a free answer to the player. /// </summary> public string FreeTrivia() { return question.Freetrivia; } // This method tells the player whether they were correct or not. private void CorrectOrNot() { if (this.usersAnswer == question.CorrectAnswer.ToString()) MessageBox.Show("Correct"); else MessageBox.Show("Incorrect"); } // Displays the questions and answers on the form. private void QuestionOutputter() { this.txtQuestion.Text = question.QuestionText; this.txtBox0.Text = question.Answers[0]; this.txtBox1.Text = question.Answers[1]; this.txtBox2.Text = question.Answers[2]; this.txtBox3.Text = question.Answers[3]; } // Clears the TextBoxes and displays a new random question. private void btnNext_Click(object sender, EventArgs e) { this.usersAnswer = txtAnswer.Text; CorrectOrNot(); this.txtQuestion.Clear(); this.txtBox0.Clear(); this.txtBox1.Clear(); this.txtBox2.Clear(); this.txtBox3.Clear(); this.txtAnswer.Clear(); this.txtAnswer.Focus(); QuestionRandomizer(); QuestionOutputter(); this.txtsuc.Text = SuccessOrFail(false).ToString(); } // Choose a random number and assign the corresponding data to question, refreshes the list if all questions used. private void QuestionRandomizer() { if (pickedQuestion.Count < trivia.AllQuestions.Count) { int random; do { random = rand.Next(trivia.AllQuestions.Count); } while (pickedQuestion.Contains(random)); pickedQuestion.Add(random); this.question = trivia.AllQuestions.ToArray()[random]; if (pickedQuestion.Count == trivia.AllQuestions.ToArray().Length) pickedQuestion.Clear(); } } } } My question is how to make it so that the code asks the user 3 or 5 questions and then returns whether the user won or not? I was wondering if somehow I could make a public void that would just make the form pop up and ask the user 3 to 5 questions and then once it asks the maximum number of questions, to close and then have a method that returns true if the user won, or false if they didn't. But I literally have no idea how to do that. Edit: So I know a for loop can make code run more than once. But the problem I'm having is, is that I don't know how to make it so that the trivia game asks 3 to 5 questions BEFORE returning something.

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  • A column ID occurred more than once in the specification

    - by Puzzle84
    Recently i've picked up my EF 4.1 / MVC 3 project again and started building in actual frontend capabilities. Now i'm developing a "simple" message system but upon going to that page i get the error as stated in the title EDIT It creates the database just not the models. Stack trace: [NullReferenceException: Object reference not set to an instance of an object.] ASP._Page_Views_Inbox_Index_cshtml.Execute() in c:\Development\MVC\DOCCL\Views\Inbox\Index.cshtml:18 System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197 System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +81 System.Web.WebPages.StartPage.RunPage() +17 System.Web.WebPages.StartPage.ExecutePageHierarchy() +62 System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +76 System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +222 System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +115 System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +295 System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13 System.Web.Mvc.<c_DisplayClass1c.b_19() +23 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func1 continuation) +242 System.Web.Mvc.<>c__DisplayClass1e.<InvokeActionResultWithFilters>b__1b() +21 System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList1 filters, ActionResult actionResult) +177 System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +324 System.Web.Mvc.Controller.ExecuteCore() +106 System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +91 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +10 System.Web.Mvc.<c_DisplayClassb.b_5() +34 System.Web.Mvc.Async.<c_DisplayClass1.b_0() +19 System.Web.Mvc.Async.<c_DisplayClass81.<BeginSynchronous>b__7(IAsyncResult _) +10 System.Web.Mvc.Async.WrappedAsyncResult1.End() +62 System.Web.Mvc.<c_DisplayClasse.b_d() +48 System.Web.Mvc.SecurityUtil.b_0(Action f) +7 System.Web.Mvc.SecurityUtil.ProcessInApplicationTrust(Action action) +22 System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +60 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9 System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9478661 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +178 InnerException : {"A column ID occurred more than once in the specification."} The recently added code is. Controller: // // GET: /Inbox/Index/5/1 public ActionResult Index(int? Id, int Page = 1) { try { const int pageSize = 10; var messages = from m in horseTracker.Messages where m.ReceiverId.Equals(Id) select m; var paginatedMessages = new PaginatedList<Message>(messages, Page, pageSize); return View(paginatedMessages); } catch (Exception ex) { } return View(); } Models public class Message { [Key] public int Id { get; set; } [Required(ErrorMessage = "Subject is required")] [Display(Name = "Subject")] public string Subject { get; set; } [Required(ErrorMessage = "Message is required")] [Display(Name = "Message")] public string Content { get; set; } [Required] [Display(Name = "Date")] public DateTime Created { get; set; } public Boolean Read { get; set; } [Required(ErrorMessage = "Can't create a message without a user")] public int SenderId { get; set; } public virtual User Sender { get; set; } [Required(ErrorMessage = "Please pick a recipient")] public int ReceiverId { get; set; } public virtual User Receiver { get; set; } } public class User { [Key] public int Id { get; set; } [Required] [Display(Name = "Username")] public string UserName { get; set; } [Required] [Display(Name = "First Name")] public string FirstName { get; set; } [Required] [Display(Name = "Last Name")] public string LastName { get; set; } [Required] [Display(Name = "E-Mail")] public string Email { get; set; } [Required] [Display(Name = "Password")] public string Password { get; set; } [Required] [Display(Name = "Country")] public string Country { get; set; } public string EMail { get; set; } //Races public virtual ICollection<Message> Messages { get; set; } } modelBuilder.Entity<User>() .HasMany(u => u.Messages) .WithRequired(m => m.Receiver) .HasForeignKey(m => m.ReceiverId) .WillCascadeOnDelete(false); Anyone have a clue on why i might be getting that error? Before i added these classes it was working fine.

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  • Only show items owned by the currently logged in user in category list view

    - by jalbasri
    I'd like to be able to provide a "Category List" view that only shows Articles that the currently logged in user owns. Is there somewhere I can edit the query used to populate the Category List view or an extension that provides this functionality. Thank you for any help you can provide. -J. Thank you for your answer. I've written the plugin. Instead of passing in an array of Articles the onContentBeforeDisplay function is called for every article and an ArrayObject of the single article gets passed in. I've been able to identify the articles I want not to be displayed but still cannot get them not to display. The $params variable has values such as "list_show_xxx" but I can't seem to change or access them. here is a var_dump($params): object(Joomla\Registry\Registry)#190 (1) { ["data":protected]=> object(stdClass)#250 (83) { ["article_layout"]=> string(9) "_:default" ["show_title"]=> string(1) "1" ["link_titles"]=> string(1) "1" ["show_intro"]=> string(1) "1" ["info_block_position"]=> string(1) "1" ["show_category"]=> string(1) "1" ["link_category"]=> string(1) "1" ["show_parent_category"]=> string(1) "0" ["link_parent_category"]=> string(1) "0" ["show_author"]=> string(1) "1" ["link_author"]=> string(1) "0" ["show_create_date"]=> string(1) "0" ["show_modify_date"]=> string(1) "0" ["show_publish_date"]=> string(1) "1" ["show_item_navigation"]=> string(1) "1" ["show_vote"]=> string(1) "0" ["show_readmore"]=> string(1) "1" ["show_readmore_title"]=> string(1) "1" ["readmore_limit"]=> string(3) "100" ["show_tags"]=> string(1) "1" ["show_icons"]=> string(1) "1" ["show_print_icon"]=> string(1) "1" ["show_email_icon"]=> string(1) "1" ["show_hits"]=> string(1) "1" ["show_noauth"]=> string(1) "0" ["urls_position"]=> string(1) "0" ["show_publishing_options"]=> string(1) "0" ["show_article_options"]=> string(1) "0" ["save_history"]=> string(1) "1" ["history_limit"]=> int(10) ["show_urls_images_frontend"]=> string(1) "0" ["show_urls_images_backend"]=> string(1) "1" ["targeta"]=> int(0) ["targetb"]=> int(0) ["targetc"]=> int(0) ["float_intro"]=> string(4) "left" ["float_fulltext"]=> string(4) "left" ["category_layout"]=> string(9) "_:default" ["show_category_heading_title_text"]=> string(1) "1" ["show_category_title"]=> string(1) "0" ["show_description"]=> string(1) "0" ["show_description_image"]=> string(1) "0" ["maxLevel"]=> string(1) "1" ["show_empty_categories"]=> string(1) "0" ["show_no_articles"]=> string(1) "1" ["show_subcat_desc"]=> string(1) "1" ["show_cat_num_articles"]=> string(1) "0" ["show_base_description"]=> string(1) "1" ["maxLevelcat"]=> string(2) "-1" ["show_empty_categories_cat"]=> string(1) "0" ["show_subcat_desc_cat"]=> string(1) "1" ["show_cat_num_articles_cat"]=> string(1) "1" ["num_leading_articles"]=> string(1) "1" ["num_intro_articles"]=> string(1) "4" ["num_columns"]=> string(1) "1" ["num_links"]=> string(1) "4" ["multi_column_order"]=> string(1) "0" ["show_subcategory_content"]=> string(1) "0" ["show_pagination_limit"]=> string(1) "1" ["filter_field"]=> string(5) "title" ["show_headings"]=> string(1) "1" ["list_show_date"]=> string(1) "0" ["date_format"]=> string(0) "" ["list_show_hits"]=> string(1) "1" ["list_show_author"]=> string(1) "1" ["orderby_pri"]=> string(5) "order" ["orderby_sec"]=> string(5) "rdate" ["order_date"]=> string(9) "published" ["show_pagination"]=> string(1) "2" ["show_pagination_results"]=> string(1) "1" ["show_feed_link"]=> string(1) "1" ["feed_summary"]=> string(1) "0" ["feed_show_readmore"]=> string(1) "0" ["display_num"]=> string(2) "10" ["menu_text"]=> int(1) ["show_page_heading"]=> int(0) ["secure"]=> int(0) ["page_title"]=> string(16) "Non-K2 News List" ["page_description"]=> string(33) "Bahrain Business Incubator Centre" ["page_rights"]=> NULL ["robots"]=> NULL ["access-edit"]=> bool(true) ["access-view"]=> bool(true) } } I've tried $params-data-list_show_author = "0" but then the page doesn't load, problem is accessing and changing the variables in $param. So the last step is to figure out how not to show the article. Any ideas?

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  • what is mistakes/errors in this code c++ tell me the correction ??

    - by jeje
    hello all here in this code the compiler print error : 132 C:.... `createlist' undeclared (first use this function) (Each undeclared identifier is reported only once for each function it appears in.) and repeat it again in all calls in main function :( what's the problem ?? plzzzz help me #include<iostream> #include<string> using namespace std; template <typename T> struct Node { T num; struct Node<T> *next; // to craet list nodes void createlist(Node<T> *p) { T data; for( ; ; ) // its containue until user want to stop { cout<<"enter data number or '#' to stop\n"; cin>>data; if(data == '#') { p->next =NULL; break; } else { p->num= data; p->next = new Node<T>; p=p->next; } } } //count list to use it in sort function int countlist (Node<T> *p) { int count=0; while(p->next != NULL) { count++; p=p->next; } return count; } // sort list void sort( Node<T> *p) { Node<T> *p1, *p2; //element 1 & 2 to compare between them int i, j , n; T temp; n= countlist(p); for( i=1; i<n ; i++) { // here every loop time we put the first element in list in p1 and the second in p2 p1=p; p2=p->next; for(j=1; j<=(n-i) ; j++) { if( p1->num > p2->num) { temp=p2->num; p2->num=p1->num; p1->num=temp; } } p1= p1->next; p2= p2->next; } } //add new number in any location the user choose void insertatloc(Node<T> *p) { T n; //read new num int loc; //read the choosen location Node<T> *locadd, *newnum, *temp; cout <<" enter location you want ..! \n"; cin>>loc; locadd=NULL; //make it null to checked if there is location after read it from user ot not while(p->next !=NULL) { if( p->next==loc) { locadd=p; break; } p=p->next; } if (locadd==NULL) {cout<<" cannot find the location\n";} else //if location is right {cout<<" enter new number\n"; // new number to creat also new location for it cin>>n; newnum= new Node/*<T>*/; newnum->num=n; temp= locadd->next; locadd->next=newnum; newnum->next=temp; } locadd->num=sort(locadd); // call sort function } // display all list nodes void displaylist (Node<T> *p) { while (p->next != NULL) { cout<<" the list contain:\n"; cout<<p->num<<endl; p=p->next; } } };//end streuct int main() { cout<<"*** Welcome in Linked List Sheet 2****\n"; // defined pointer for structer Node // that value is the address of first node struct Node<int>*mynodes= new struct Node<int>; // create nodes in mynodes list cout<<"\nCreate nodes in list"; createlist(mynodes); // insert node in location insertatloc(mynodes); /* count the number of all nodes nodescount = countlist(mynodes); cout<<"\nThe number of nodes in list is: "<<nodescount;*/ // sort nodes in list sort(mynodes); // Display nodes cout<<"\nDisplay all nodes in list:\n"; displaylist(mynodes); system("pause"); return 0; }

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  • Change English numbers to Persian and vice versa in MVC (httpmodule)?

    - by Mohammad
    I wanna change all English numbers to Persian for showing to users. and change them to English numbers again for giving all requests (Postbacks) e.g: we have something like this in view IRQ170, I wanna show IRQ??? to users and give IRQ170 from users. I know, I have to use Httpmodule, But I don't know how ? Could you please guide me? Edit : Let me describe more : I've written the following http module : using System; using System.Collections.Specialized; using System.Diagnostics; using System.IO; using System.Text; using System.Text.RegularExpressions; using System.Web; using System.Web.UI; using Smartiz.Common; namespace Smartiz.UI.Classes { public class PersianNumberModule : IHttpModule { private StreamWatcher _watcher; #region Implementation of IHttpModule /// <summary> /// Initializes a module and prepares it to handle requests. /// </summary> /// <param name="context">An <see cref="T:System.Web.HttpApplication"/> that provides access to the methods, properties, and events common to all application objects within an ASP.NET application </param> public void Init(HttpApplication context) { context.BeginRequest += ContextBeginRequest; context.EndRequest += ContextEndRequest; } /// <summary> /// Disposes of the resources (other than memory) used by the module that implements <see cref="T:System.Web.IHttpModule"/>. /// </summary> public void Dispose() { } #endregion private void ContextBeginRequest(object sender, EventArgs e) { HttpApplication context = sender as HttpApplication; if (context == null) return; _watcher = new StreamWatcher(context.Response.Filter); context.Response.Filter = _watcher; } private void ContextEndRequest(object sender, EventArgs e) { HttpApplication context = sender as HttpApplication; if (context == null) return; _watcher = new StreamWatcher(context.Response.Filter); context.Response.Filter = _watcher; } } public class StreamWatcher : Stream { private readonly Stream _stream; private readonly MemoryStream _memoryStream = new MemoryStream(); public StreamWatcher(Stream stream) { _stream = stream; } public override void Flush() { _stream.Flush(); } public override int Read(byte[] buffer, int offset, int count) { int bytesRead = _stream.Read(buffer, offset, count); string orgContent = Encoding.UTF8.GetString(buffer, offset, bytesRead); string newContent = orgContent.ToEnglishNumber(); int newByteCountLength = Encoding.UTF8.GetByteCount(newContent); Encoding.UTF8.GetBytes(newContent, 0, Encoding.UTF8.GetByteCount(newContent), buffer, 0); return newByteCountLength; } public override void Write(byte[] buffer, int offset, int count) { string strBuffer = Encoding.UTF8.GetString(buffer, offset, count); MatchCollection htmlAttributes = Regex.Matches(strBuffer, @"(\S+)=[""']?((?:.(?![""']?\s+(?:\S+)=|[>""']))+.)[""']?", RegexOptions.IgnoreCase | RegexOptions.Multiline); foreach (Match match in htmlAttributes) { strBuffer = strBuffer.Replace(match.Value, match.Value.ToEnglishNumber()); } MatchCollection scripts = Regex.Matches(strBuffer, "<script[^>]*>(.*?)</script>", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace); foreach (Match match in scripts) { MatchCollection values = Regex.Matches(match.Value, @"([""'])(?:(?=(\\?))\2.)*?\1", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace); foreach (Match stringValue in values) { strBuffer = strBuffer.Replace(stringValue.Value, stringValue.Value.ToEnglishNumber()); } } MatchCollection styles = Regex.Matches(strBuffer, "<style[^>]*>(.*?)</style>", RegexOptions.Singleline | RegexOptions.IgnoreCase | RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace); foreach (Match match in styles) { strBuffer = strBuffer.Replace(match.Value, match.Value.ToEnglishNumber()); } byte[] data = Encoding.UTF8.GetBytes(strBuffer); _memoryStream.Write(data, offset, count); _stream.Write(data, offset, count); } public override string ToString() { return Encoding.UTF8.GetString(_memoryStream.ToArray()); } #region Rest of the overrides public override bool CanRead { get { throw new NotImplementedException(); } } public override bool CanSeek { get { throw new NotImplementedException(); } } public override bool CanWrite { get { throw new NotImplementedException(); } } public override long Seek(long offset, SeekOrigin origin) { throw new NotImplementedException(); } public override void SetLength(long value) { throw new NotImplementedException(); } public override long Length { get { throw new NotImplementedException(); } } public override long Position { get { throw new NotImplementedException(); } set { throw new NotImplementedException(); } } #endregion } } It works well, but It converts all numbers in css and scripts files to Persian and it causes error.

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  • Class structure for the proposed data and its containers ?

    - by Prix
    First I would like to wish a happy new year to everyone that may read this :) I am having trouble on how to make a container for some data that I am importing into my application, and I am not sure on how to explain this very well and my english is not really a that good so I hope you can bear with my mistake and help me with some guidance. Currently with a foreach I am importing the follow fields from the data I receive: guid, itemid, name, owner(optional, can be null), zoneid, titleid, subid, heading, x, y, z, typeA, typeB, typeC From the above fields I need to store a Waypoint list of all coords a given item has moved to BUT for each guid I have a new list of waypoints. And from the waypoint list the first entry is also my initial item start location which would be my item initial position (if you notice i have a separate list for it which I was not sure would be better or not) not all items have a waypoint list but all items have the first position. So the first idea I came with to store this data was a list with a class with 2 inner classes with their list: public List<ItemList> myList = new List<ItemList>(); public class ItemList { public int guid { get; set; } public int itemid { get; set; } public string name { get; set; } public int titleid { get; set; } public itemType status { get; set; } public class Waypoint { public float posX { get; set; } public float posY { get; set; } public float posZ { get; set; } } public List<Waypoint> waypoint = new List<Waypoint>(); public class Location { public int zone { get; set; } public int subid { get; set; } public int heading { get; set; } public float posX { get; set; } public float posY { get; set; } public float posZ { get; set; } } public List<Location> position = new List<Location>(); } So here is an example of how I would add a new waypoint to a GUID that exists in the list bool itemExists = myList.Exists(item => item.guid == guid && item.itemid == itemid); if (itemExists) { int lastDistance = 3; ItemList.Waypoint nextWaypoint; ItemList myItem = myList.Find(item => item.guid == guid && item.itemid == itemid); if (myItem.waypoint.Count == 0) { nextWaypoint = new ItemList.Waypoint(); nextWaypoint.posX = PosX; nextWaypoint.posY = PosY; nextWaypoint.posZ = PosZ; } else { ItemList.Waypoint lastWaypoint = myItem.waypoint[myItem.waypoint.Count - 1]; if (lastWaypoint != null) { lastDistance = getDistance(x, y, z, lastWaypoint.posX, lastWaypoint.posY, lastWaypoint.posZ); } if (lastDistance > 2) { nextWaypoint = new ItemList.Waypoint(); nextWaypoint.posX = PosX; nextWaypoint.posY = PosY; nextWaypoint.posZ = PosZ; } } myItem.waypoint.Add(nextWaypoint); } Then to register a new item I would take advantage of the itemExist above so I won't register the same GUID again: ItemList newItem = new ItemList(); newItem.guid = guid; newItem.itemid = itemid; newItem.name = name; newItem.status = status; newItem.titleid = titleid; // Item location ItemList.Location itemLocation = new ItemList.Location(); itemLocation.subid = 0; itemLocation.zone= zone; itemLocation.heading = convertHeading(Heading); itemLocation.posX = PosX; itemLocation.posY = PosY; itemLocation.posZ = PosZ; newItem.position.Add(itemLocation); myList.Add(newItem); Could you help me with advices on how my class structure and lists should look like ? Are there better ways to interate with the lists to get lastWaypoint of a GUID or verify wether an item exist or not ? What else would you advise me in general ? PS: If you have any questions or if there is something I missed to post please let me know and I will update it.

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  • JAVA-SQL- Data Migration - ResultSets comparing Failing JUnit test

    - by user1865053
    I CANNOT get this JUnit Test to pass for the life of me. Can somebody point out where this has gone wrong. I am doing a data migration(MSSQL SERVER 2005), but I have the sourceDBUrl and the targetDCUrl the same URL so to narrow it down to syntax errors. So that is what I have, a syntax error. I am comparing the results of a table for the query SELECT programmeapproval, resourceapproval FROM tr_timesheet WHERE timesheetid = ? and the test always fails, but passes for other junit tests I have developed. I created 3 diffemt resultSetsEqual methods and none work. Yet, some other JUnit tests I have developed have PASSED. THE QUERY: SELECT timesheetid, programmeapproval, resourceapproval FROM tr_timesheet Returns three columns timesheetid (PK,int, not null) (populated with a range of numbers 2240 - 2282) programmeapproval (smallint,not null) (populated with the number 1 in every field) resourceapproval (smallint, not null) (populated with a number 1 in every field) When I run the query that is embedded in the code it only returns one row with the programmeapproval and resourceapproval columns and both field populated with the number 1. I have all jdbc drivers correctly installed and tested for connectivity. The JUnit Test is failing at this point according to the IDE. assertTrue(helper.resultSetsEqual2(sourceVal,targetVal)); This is the code: /*THIS IS A JUNIT CLASS****? package a7.unittests.dao; import static org.junit.Assert.assertTrue; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.Types; import org.junit.Test; import artemispm.tritonalerts.TimesheetAlert; public class UnitTestTimesheetAlert { @Test public void testQUERY_CHECKALERT() throws Exception{ UnitTestHelper helper = new UnitTestHelper(); Connection con = helper.getConnection(helper.sourceDBUrl); Connection conTarget = helper.getConnection(helper.targetDBUrl); PreparedStatement stmt = con.prepareStatement("select programmeapproval, resourceapproval from tr_timesheet where timesheetid = ?"); stmt.setInt(1, 2240); ResultSet sourceVal = stmt.executeQuery(); stmt = conTarget.prepareStatement("select programmeapproval, resourceapproval from tr_timesheet where timesheetid = ?"); stmt.setInt(1,2240); ResultSet targetVal = stmt.executeQuery(); assertTrue(helper.resultSetsEqual2(sourceVal,targetVal)); }} /*END**/ /*THIS IS A REGULAR CLASS**/ package a7.unittests.dao; import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.ResultSetMetaData; import java.sql.SQLException; public class UnitTestHelper { static String sourceDBUrl = "jdbc:sqlserver://127.0.0.1:1433;databaseName=a7itm;user=a7user;password=a7user"; static String targetDBUrl = "jdbc:sqlserver://127.0.0.1:1433;databaseName=a7itm;user=a7user;password=a7user"; public Connection getConnection(String url)throws Exception{ return DriverManager.getConnection(url); } public boolean resultSetsEqual3 (ResultSet rs1, ResultSet rs2) throws SQLException { int col = 1; //ResultSetMetaData metadata = rs1.getMetaData(); //int count = metadata.getColumnCount(); while (rs1.next() && rs2.next()) { final Object res1 = rs1.getObject(col); final Object res2 = rs2.getObject(col); // Check values if (!res1.equals(res2)) { throw new RuntimeException(String.format("%s and %s aren't equal at common position %d", res1, res2, col)); } // rs1 and rs2 must reach last row in the same iteration if ((rs1.isLast() != rs2.isLast())) { throw new RuntimeException("The two ResultSets contains different number of columns!"); } } return true; } public boolean resultSetsEqual (ResultSet source, ResultSet target) throws SQLException{ while(source.next()) { target.next(); ResultSetMetaData metadata = source.getMetaData(); int count = metadata.getColumnCount(); for (int i =1; i<=count; i++) { if(source.getObject(i) != target.getObject(i)) { return false; } } } return true; } public boolean resultSetsEqual2 (ResultSet source, ResultSet target) throws SQLException{ while(source.next()) { target.next(); ResultSetMetaData metadata = source.getMetaData(); int count = metadata.getColumnCount(); for (int i =1; i<=count; i++) { if(source.getObject(i).equals(target.getObject(i))) { return false; } } } return true; } } /END***/ /*PASTED NEW CLASS - THIS IS A JUNIT TEST CLASS*/ package a7.unittests.dao; import static org.junit.Assert.*; import java.sql.Connection; import java.sql.DriverManager; import org.junit.Test; public class TestDatabaseConnection { @Test public void testConnection() throws Exception{ UnitTestHelper helper = new UnitTestHelper(); Connection con = helper.getConnection(helper.sourceDBUrl); Connection conTarget = helper.getConnection(helper.targetDBUrl); assertTrue(con != null && conTarget != null); } } /**END***/

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  • Loop crashing program having to do with 2D arrays

    - by user450062
    I am creating an encoding program and when I instruct the program to create a 5X5 grid based on the alphabet while skipping over letters that match up to certain pre-defined variables(which are given values by user input during runtime). I have a loop that instructs the loop to keep running until the values that access the array are out of bounds, the loop seems to cause the problem. This code is standardized so there shouldn't be much trouble compiling it in another compiler. Also would it be better to seperate my program into functions? here is the code: #include<iostream> #include<fstream> #include<cstdlib> #include<string> #include<limits> using namespace std; int main(){ while (!cin.fail()) { char type[81]; char filename[20]; char key [5]; char f[2] = "q"; char g[2] = "q"; char h[2] = "q"; char i[2] = "q"; char j[2] = "q"; char k[2] = "q"; char l[2] = "q"; int a = 1; int b = 1; int c = 1; int d = 1; int e = 1; string cipherarraytemplate[5][5]= { {"a","b","c","d","e"}, {"f","g","h","i","j"}, {"k","l","m","n","o"}, {"p","r","s","t","u"}, {"v","w","x","y","z"} }; string cipherarray[5][5]= { {"a","b","c","d","e"}, {"f","g","h","i","j"}, {"k","l","m","n","o"}, {"p","r","s","t","u"}, {"v","w","x","y","z"} }; cout<<"Enter the name of a file you want to create.\n"; cin>>filename; ofstream outFile; outFile.open(filename); outFile<<fixed; outFile.precision(2); outFile.setf(ios_base::showpoint); cin.ignore(std::numeric_limits<int>::max(),'\n'); cout<<"enter your codeword(codeword can have no repeating letters)\n"; cin>>key; while (key[a] != '\0' ){ while(b < 6){ cipherarray[b][c] = key[a]; if ( f == "q" ) { cipherarray[b][c] = f; } if ( f != "q" && g == "q" ) { cipherarray[b][c] = g; } if ( g != "q" && h == "q" ) { cipherarray[b][c] = h; } if ( h != "q" && i == "q" ) { cipherarray[b][c] = i; } if ( i != "q" && j == "q" ) { cipherarray[b][c] = j; } if ( j != "q" && k == "q" ) { cipherarray[b][c] = k; } if ( k != "q" && l == "q" ) { cipherarray[b][c] = l; } a++; b++; } c++; b = 1; } while (c < 6 || b < 6){ if (cipherarraytemplate[d][e] == f || cipherarraytemplate[d][e] == g || cipherarraytemplate[d][e] == h || cipherarraytemplate[d][e] == i || cipherarraytemplate[d][e] == j || cipherarraytemplate[d][e] == k || cipherarraytemplate[d][e] == l){ d++; } else { cipherarray[b][c] = cipherarraytemplate[d][e]; d++; b++; } if (d == 6){ d = 1; e++; } if (b == 6){ c++; b = 1; } } cout<<"now enter some text."<<endl<<"To end this program press Crtl-Z\n"; while(!cin.fail()){ cin.getline(type,81); outFile<<type<<endl; } outFile.close(); } } I know there is going to be some mid-forties guy out there who is going to stumble on to this post, he's have been programming for 20-some years and he's going to look at my code and say: "what is this guy doing".

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  • How to get data from dynamically created EditText views and insert it into an array?

    - by Snwspeckle
    So basically what I need my program to do at this point is that when I click the submit button, I need to loop through each dynamic row of the ListView and grab the value in the EditText view and then insert that into an array which I will do further calculations after. Here is my code right now. package com.hello_world; import java.util.ArrayList; import com.hello_world.ByteInputActivity.MyAdapter.ViewHolder; import android.app.Activity; import android.content.Context; import android.os.Bundle; import android.util.Log; import android.view.KeyEvent; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnFocusChangeListener; import android.view.View.OnKeyListener; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.TextView; public class ByteInputActivity extends Activity { private ListView myList; private MyAdapter myAdapter; private Integer resQuestions; private Integer indexVal = 0; private View caption; ViewHolder holder; ArrayList<Integer> intArrayList = new ArrayList<Integer>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.fieldlist); //Gets number of questions from MainActivity Bundle extras = getIntent().getExtras(); if(extras !=null) { resQuestions = extras.getInt("index"); } myList = (ListView) findViewById(R.id.FieldList); myList.setItemsCanFocus(true); myAdapter = new MyAdapter(); myList.setAdapter(myAdapter); Button submit = (Button) findViewById(R.id.btn_New); submit.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { for (int i = 0; i < myList.getCount() ; i++) { View vListSortOrder; vListSortOrder = myList.getChildAt(i); String temp = holder.caption.getText().toString(); Log.e("VALUES", "" +temp); } } }); } public class MyAdapter extends BaseAdapter { private LayoutInflater mInflater; public ArrayList myItems = new ArrayList(); public MyAdapter() { mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); for (int i = 0; i < resQuestions; i++) { ListItem listItem = new ListItem(); listItem.caption = "Index " + i; listItem.indexText = "Index " + i; myItems.add(listItem); indexVal += 1; } notifyDataSetChanged(); } public int getCount() { return myItems.size(); } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { if (convertView == null) { holder = new ViewHolder(); convertView = mInflater.inflate(R.layout.item, null); holder.indexText = (TextView) convertView .findViewById(R.id.textView1); holder.caption = (EditText) convertView .findViewById(R.id.ItemCaption); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } //Fill EditText with the value you have in data source holder.caption.setText(""); holder.caption.setId(position); holder.indexText.setText("Index " + position); holder.indexText.setId(position); //we need to update adapter once we finish with editing holder.caption.setOnFocusChangeListener(new OnFocusChangeListener() { public void onFocusChange(View v, boolean hasFocus) { if (!hasFocus){ final int position = v.getId(); final EditText Caption = (EditText) v; myItems.set(position, Caption.getText().toString()); } } }); return convertView; } class ViewHolder { EditText caption; TextView indexText; } class ListItem { String caption; String indexText; } } }

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  • collsion issues with quadtree [on hold]

    - by QuantumGamer
    So i implemented a Quad tree in Java for my 2D game and everything works fine except for when i run my collision detection algorithm, which checks if a object has hit another object and which side it hit.My problem is 80% of the time the collision algorithm works but sometimes the objects just go through each other. Here is my method: private void checkBulletCollision(ArrayList object) { quad.clear(); // quad is the quadtree object for(int i=0; i < object.size();i++){ if(object.get(i).getId() == ObjectId.Bullet) // inserts the object into quadtree quad.insert((Bullet)object.get(i)); } ArrayList<GameObject> returnObjects = new ArrayList<>(); // Uses Quadtree to determine to calculate how many // other bullets it can collide with for(int i=0; i < object.size(); i++){ returnObjects.clear(); if(object.get(i).getId() == ObjectId.Bullet){ quad.retrieve(returnObjects, object.get(i).getBoundsAll()); for(int k=0; k < returnObjects.size(); k++){ Bullet bullet = (Bullet) returnObjects.get(k); if(getBoundsTop().intersects(bullet.getBoundsBottom())){ vy = speed; bullet.vy = -speed; } if(getBoundsBottom().intersects(bullet.getBoundsTop())){ vy = -speed; bullet.vy = speed; } if(getBoundsLeft().intersects(bullet.getBoundsRight())){ vx =speed; bullet.vx = -speed; } if(getBoundsRight().intersects(bullet.getBoundsLeft())){ vx = -speed; bullet.vx = speed; } } } } } Any help would be appreciated. Thanks in advance.

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  • ASP.NET MVC Paging/Sorting/Filtering using the MVCContrib Grid and Pager

    - by rajbk
    This post walks you through creating a UI for paging, sorting and filtering a list of data items. It makes use of the excellent MVCContrib Grid and Pager Html UI helpers. A sample project is attached at the bottom. Our UI will eventually look like this. The application will make use of the Northwind database. The top portion of the page has a filter area region. The filter region is enclosed in a form tag. The select lists are wired up with jQuery to auto post back the form. The page has a pager region at the top and bottom of the product list. The product list has a link to display more details about a given product. The column headings are clickable for sorting and an icon shows the sort direction. Strongly Typed View Models The views are written to expect strongly typed objects. We suffix these strongly typed objects with ViewModel since they are designed specifically for passing data down to the view.  The following listing shows the ProductViewModel. This class will be used to hold information about a Product. We use attributes to specify if the property should be hidden and what its heading in the table should be. This metadata will be used by the MvcContrib Grid to render the table. Some of the properties are hidden from the UI ([ScaffoldColumn(false)) but are needed because we will be using those for filtering when writing our LINQ query. public ActionResult Index( string productName, int? supplierID, int? categoryID, GridSortOptions gridSortOptions, int? page) {   var productList = productRepository.GetProductsProjected();   // Set default sort column if (string.IsNullOrWhiteSpace(gridSortOptions.Column)) { gridSortOptions.Column = "ProductID"; }   // Filter on SupplierID if (supplierID.HasValue) { productList = productList.Where(a => a.SupplierID == supplierID); }   // Filter on CategoryID if (categoryID.HasValue) { productList = productList.Where(a => a.CategoryID == categoryID); }   // Filter on ProductName if (!string.IsNullOrWhiteSpace(productName)) { productList = productList.Where(a => a.ProductName.Contains(productName)); }   // Create all filter data and set current values if any // These values will be used to set the state of the select list and textbox // by sending it back to the view. var productFilterViewModel = new ProductFilterViewModel(); productFilterViewModel.SelectedCategoryID = categoryID ?? -1; productFilterViewModel.SelectedSupplierID = supplierID ?? -1; productFilterViewModel.Fill();   // Order and page the product list var productPagedList = productList .OrderBy(gridSortOptions.Column, gridSortOptions.Direction) .AsPagination(page ?? 1, 10);     var productListContainer = new ProductListContainerViewModel { ProductPagedList = productPagedList, ProductFilterViewModel = productFilterViewModel, GridSortOptions = gridSortOptions };   return View(productListContainer); } The following diagram shows the rest of the key ViewModels in our design. We have a container class called ProductListContainerViewModel which has nested classes. The ProductPagedList is of type IPagination<ProductViewModel>. The MvcContrib expects the IPagination<T> interface to determine the page number and page size of the collection we are working with. You convert any IEnumerable<T> into an IPagination<T> by calling the AsPagination extension method in the MvcContrib library. It also creates a paged set of type ProductViewModel. The ProductFilterViewModel class will hold information about the different select lists and the ProductName being searched on. It will also hold state of any previously selected item in the lists and the previous search criteria (you will recall that this type of state information was stored in Viewstate when working with WebForms). With MVC there is no state storage and so all state has to be fetched and passed back to the view. The GridSortOptions is a type defined in the MvcContrib library and is used by the Grid to determine the current column being sorted on and the current sort direction. The following shows the view and partial views used to render our UI. The Index view expects a type ProductListContainerViewModel which we described earlier. <%Html.RenderPartial("SearchFilters", Model.ProductFilterViewModel); %> <% Html.RenderPartial("Pager", Model.ProductPagedList); %> <% Html.RenderPartial("SearchResults", Model); %> <% Html.RenderPartial("Pager", Model.ProductPagedList); %> The View contains a partial view “SearchFilters” and passes it the ProductViewFilterContainer. The SearchFilter uses this Model to render all the search lists and textbox. The partial view “Pager” uses the ProductPageList which implements the interface IPagination. The “Pager” view contains the MvcContrib Pager helper used to render the paging information. This view is repeated twice since we want the pager UI to be available at the top and bottom of the product list. The Pager partial view is located in the Shared directory so that it can be reused across Views. The partial view “SearchResults” uses the ProductListContainer model. This partial view contains the MvcContrib Grid which needs both the ProdctPagedList and GridSortOptions to render itself. The Controller Action An example of a request like this: /Products?productName=test&supplierId=29&categoryId=4. The application receives this GET request and maps it to the Index method of the ProductController. Within the action we create an IQueryable<ProductViewModel> by calling the GetProductsProjected() method. /// <summary> /// This method takes in a filter list, paging/sort options and applies /// them to an IQueryable of type ProductViewModel /// </summary> /// <returns> /// The return object is a container that holds the sorted/paged list, /// state for the fiters and state about the current sorted column /// </returns> public ActionResult Index( string productName, int? supplierID, int? categoryID, GridSortOptions gridSortOptions, int? page) {   var productList = productRepository.GetProductsProjected();   // Set default sort column if (string.IsNullOrWhiteSpace(gridSortOptions.Column)) { gridSortOptions.Column = "ProductID"; }   // Filter on SupplierID if (supplierID.HasValue) { productList.Where(a => a.SupplierID == supplierID); }   // Filter on CategoryID if (categoryID.HasValue) { productList = productList.Where(a => a.CategoryID == categoryID); }   // Filter on ProductName if (!string.IsNullOrWhiteSpace(productName)) { productList = productList.Where(a => a.ProductName.Contains(productName)); }   // Create all filter data and set current values if any // These values will be used to set the state of the select list and textbox // by sending it back to the view. var productFilterViewModel = new ProductFilterViewModel(); productFilterViewModel.SelectedCategoryID = categoryID ?? -1; productFilterViewModel.SelectedSupplierID = supplierID ?? -1; productFilterViewModel.Fill();   // Order and page the product list var productPagedList = productList .OrderBy(gridSortOptions.Column, gridSortOptions.Direction) .AsPagination(page ?? 1, 10);     var productListContainer = new ProductListContainerViewModel { ProductPagedList = productPagedList, ProductFilterViewModel = productFilterViewModel, GridSortOptions = gridSortOptions };   return View(productListContainer); } The supplier, category and productname filters are applied to this IQueryable if any are present in the request. The ProductPagedList class is created by applying a sort order and calling the AsPagination method. Finally the ProductListContainerViewModel class is created and returned to the view. You have seen how to use strongly typed views with the MvcContrib Grid and Pager to render a clean lightweight UI with strongly typed views. You also saw how to use partial views to get data from the strongly typed model passed to it from the parent view. The code also shows you how to use jQuery to auto post back. The sample is attached below. Don’t forget to change your connection string to point to the server containing the Northwind database. NorthwindSales_MvcContrib.zip My name is Kobayashi. I work for Keyser Soze.

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  • Agile Development

    - by James Oloo Onyango
    Alot of literature has and is being written about agile developement and its surrounding philosophies. In my quest to find the best way to express the importance of agile methodologies, i have found Robert C. Martin's "A Satire Of Two Companies" to be both the most concise and thorough! Enjoy the read! Rufus Inc Project Kick Off Your name is Bob. The date is January 3, 2001, and your head still aches from the recent millennial revelry. You are sitting in a conference room with several managers and a group of your peers. You are a project team leader. Your boss is there, and he has brought along all of his team leaders. His boss called the meeting. "We have a new project to develop," says your boss's boss. Call him BB. The points in his hair are so long that they scrape the ceiling. Your boss's points are just starting to grow, but he eagerly awaits the day when he can leave Brylcream stains on the acoustic tiles. BB describes the essence of the new market they have identified and the product they want to develop to exploit this market. "We must have this new project up and working by fourth quarter October 1," BB demands. "Nothing is of higher priority, so we are cancelling your current project." The reaction in the room is stunned silence. Months of work are simply going to be thrown away. Slowly, a murmur of objection begins to circulate around the conference table.   His points give off an evil green glow as BB meets the eyes of everyone in the room. One by one, that insidious stare reduces each attendee to quivering lumps of protoplasm. It is clear that he will brook no discussion on this matter. Once silence has been restored, BB says, "We need to begin immediately. How long will it take you to do the analysis?" You raise your hand. Your boss tries to stop you, but his spitwad misses you and you are unaware of his efforts.   "Sir, we can't tell you how long the analysis will take until we have some requirements." "The requirements document won't be ready for 3 or 4 weeks," BB says, his points vibrating with frustration. "So, pretend that you have the requirements in front of you now. How long will you require for analysis?" No one breathes. Everyone looks around to see whether anyone has some idea. "If analysis goes beyond April 1, we have a problem. Can you finish the analysis by then?" Your boss visibly gathers his courage: "We'll find a way, sir!" His points grow 3 mm, and your headache increases by two Tylenol. "Good." BB smiles. "Now, how long will it take to do the design?" "Sir," you say. Your boss visibly pales. He is clearly worried that his 3 mms are at risk. "Without an analysis, it will not be possible to tell you how long design will take." BB's expression shifts beyond austere.   "PRETEND you have the analysis already!" he says, while fixing you with his vacant, beady little eyes. "How long will it take you to do the design?" Two Tylenol are not going to cut it. Your boss, in a desperate attempt to save his new growth, babbles: "Well, sir, with only six months left to complete the project, design had better take no longer than 3 months."   "I'm glad you agree, Smithers!" BB says, beaming. Your boss relaxes. He knows his points are secure. After a while, he starts lightly humming the Brylcream jingle. BB continues, "So, analysis will be complete by April 1, design will be complete by July 1, and that gives you 3 months to implement the project. This meeting is an example of how well our new consensus and empowerment policies are working. Now, get out there and start working. I'll expect to see TQM plans and QIT assignments on my desk by next week. Oh, and don't forget that your crossfunctional team meetings and reports will be needed for next month's quality audit." "Forget the Tylenol," you think to yourself as you return to your cubicle. "I need bourbon."   Visibly excited, your boss comes over to you and says, "Gosh, what a great meeting. I think we're really going to do some world shaking with this project." You nod in agreement, too disgusted to do anything else. "Oh," your boss continues, "I almost forgot." He hands you a 30-page document. "Remember that the SEI is coming to do an evaluation next week. This is the evaluation guide. You need to read through it, memorize it, and then shred it. It tells you how to answer any questions that the SEI auditors ask you. It also tells you what parts of the building you are allowed to take them to and what parts to avoid. We are determined to be a CMM level 3 organization by June!"   You and your peers start working on the analysis of the new project. This is difficult because you have no requirements. But from the 10-minute introduction given by BB on that fateful morning, you have some idea of what the product is supposed to do.   Corporate process demands that you begin by creating a use case document. You and your team begin enumerating use cases and drawing oval and stick diagrams. Philosophical debates break out among the team members. There is disagreement as to whether certain use cases should be connected with <<extends>> or <<includes>> relationships. Competing models are created, but nobody knows how to evaluate them. The debate continues, effectively paralyzing progress.   After a week, somebody finds the iceberg.com Web site, which recommends disposing entirely of <<extends>> and <<includes>> and replacing them with <<precedes>> and <<uses>>. The documents on this Web site, authored by Don Sengroiux, describes a method known as stalwart-analysis, which claims to be a step-by-step method for translating use cases into design diagrams. More competing use case models are created using this new scheme, but again, people can't agree on how to evaluate them. The thrashing continues. More and more, the use case meetings are driven by emotion rather than by reason. If it weren't for the fact that you don't have requirements, you'd be pretty upset by the lack of progress you are making. The requirements document arrives on February 15. And then again on February 20, 25, and every week thereafter. Each new version contradicts the previous one. Clearly, the marketing folks who are writing the requirements, empowered though they might be, are not finding consensus.   At the same time, several new competing use case templates have been proposed by the various team members. Each template presents its own particularly creative way of delaying progress. The debates rage on. On March 1, Prudence Putrigence, the process proctor, succeeds in integrating all the competing use case forms and templates into a single, all-encompassing form. Just the blank form is 15 pages long. She has managed to include every field that appeared on all the competing templates. She also presents a 159- page document describing how to fill out the use case form. All current use cases must be rewritten according to the new standard.   You marvel to yourself that it now requires 15 pages of fill-in-the-blank and essay questions to answer the question: What should the system do when the user presses Return? The corporate process (authored by L. E. Ott, famed author of "Holistic Analysis: A Progressive Dialectic for Software Engineers") insists that you discover all primary use cases, 87 percent of all secondary use cases, and 36.274 percent of all tertiary use cases before you can complete analysis and enter the design phase. You have no idea what a tertiary use case is. So in an attempt to meet this requirement, you try to get your use case document reviewed by the marketing department, which you hope will know what a tertiary use case is.   Unfortunately, the marketing folks are too busy with sales support to talk to you. Indeed, since the project started, you have not been able to get a single meeting with marketing, which has provided a never-ending stream of changing and contradictory requirements documents.   While one team has been spinning endlessly on the use case document, another team has been working out the domain model. Endless variations of UML documents are pouring out of this team. Every week, the model is reworked.   The team members can't decide whether to use <<interfaces>> or <<types>> in the model. A huge disagreement has been raging on the proper syntax and application of OCL. Others on the team just got back from a 5-day class on catabolism, and have been producing incredibly detailed and arcane diagrams that nobody else can fathom.   On March 27, with one week to go before analysis is to be complete, you have produced a sea of documents and diagrams but are no closer to a cogent analysis of the problem than you were on January 3. **** And then, a miracle happens.   **** On Saturday, April 1, you check your e-mail from home. You see a memo from your boss to BB. It states unequivocally that you are done with the analysis! You phone your boss and complain. "How could you have told BB that we were done with the analysis?" "Have you looked at a calendar lately?" he responds. "It's April 1!" The irony of that date does not escape you. "But we have so much more to think about. So much more to analyze! We haven't even decided whether to use <<extends>> or <<precedes>>!" "Where is your evidence that you are not done?" inquires your boss, impatiently. "Whaaa . . . ." But he cuts you off. "Analysis can go on forever; it has to be stopped at some point. And since this is the date it was scheduled to stop, it has been stopped. Now, on Monday, I want you to gather up all existing analysis materials and put them into a public folder. Release that folder to Prudence so that she can log it in the CM system by Monday afternoon. Then get busy and start designing."   As you hang up the phone, you begin to consider the benefits of keeping a bottle of bourbon in your bottom desk drawer. They threw a party to celebrate the on-time completion of the analysis phase. BB gave a colon-stirring speech on empowerment. And your boss, another 3 mm taller, congratulated his team on the incredible show of unity and teamwork. Finally, the CIO takes the stage to tell everyone that the SEI audit went very well and to thank everyone for studying and shredding the evaluation guides that were passed out. Level 3 now seems assured and will be awarded by June. (Scuttlebutt has it that managers at the level of BB and above are to receive significant bonuses once the SEI awards level 3.)   As the weeks flow by, you and your team work on the design of the system. Of course, you find that the analysis that the design is supposedly based on is flawedno, useless; no, worse than useless. But when you tell your boss that you need to go back and work some more on the analysis to shore up its weaker sections, he simply states, "The analysis phase is over. The only allowable activity is design. Now get back to it."   So, you and your team hack the design as best you can, unsure of whether the requirements have been properly analyzed. Of course, it really doesn't matter much, since the requirements document is still thrashing with weekly revisions, and the marketing department still refuses to meet with you.     The design is a nightmare. Your boss recently misread a book named The Finish Line in which the author, Mark DeThomaso, blithely suggested that design documents should be taken down to code-level detail. "If we are going to be working at that level of detail," you ask, "why don't we simply write the code instead?" "Because then you wouldn't be designing, of course. And the only allowable activity in the design phase is design!" "Besides," he continues, "we have just purchased a companywide license for Dandelion! This tool enables 'Round the Horn Engineering!' You are to transfer all design diagrams into this tool. It will automatically generate our code for us! It will also keep the design diagrams in sync with the code!" Your boss hands you a brightly colored shrinkwrapped box containing the Dandelion distribution. You accept it numbly and shuffle off to your cubicle. Twelve hours, eight crashes, one disk reformatting, and eight shots of 151 later, you finally have the tool installed on your server. You consider the week your team will lose while attending Dandelion training. Then you smile and think, "Any week I'm not here is a good week." Design diagram after design diagram is created by your team. Dandelion makes it very difficult to draw these diagrams. There are dozens and dozens of deeply nested dialog boxes with funny text fields and check boxes that must all be filled in correctly. And then there's the problem of moving classes between packages. At first, these diagram are driven from the use cases. But the requirements are changing so often that the use cases rapidly become meaningless. Debates rage about whether VISITOR or DECORATOR design patterns should be used. One developer refuses to use VISITOR in any form, claiming that it's not a properly object-oriented construct. Someone refuses to use multiple inheritance, since it is the spawn of the devil. Review meetings rapidly degenerate into debates about the meaning of object orientation, the definition of analysis versus design, or when to use aggregation versus association. Midway through the design cycle, the marketing folks announce that they have rethought the focus of the system. Their new requirements document is completely restructured. They have eliminated several major feature areas and replaced them with feature areas that they anticipate customer surveys will show to be more appropriate. You tell your boss that these changes mean that you need to reanalyze and redesign much of the system. But he says, "The analysis phase is system. But he says, "The analysis phase is over. The only allowable activity is design. Now get back to it."   You suggest that it might be better to create a simple prototype to show to the marketing folks and even some potential customers. But your boss says, "The analysis phase is over. The only allowable activity is design. Now get back to it." Hack, hack, hack, hack. You try to create some kind of a design document that might reflect the new requirements documents. However, the revolution of the requirements has not caused them to stop thrashing. Indeed, if anything, the wild oscillations of the requirements document have only increased in frequency and amplitude.   You slog your way through them.   On June 15, the Dandelion database gets corrupted. Apparently, the corruption has been progressive. Small errors in the DB accumulated over the months into bigger and bigger errors. Eventually, the CASE tool just stopped working. Of course, the slowly encroaching corruption is present on all the backups. Calls to the Dandelion technical support line go unanswered for several days. Finally, you receive a brief e-mail from Dandelion, informing you that this is a known problem and that the solution is to purchase the new version, which they promise will be ready some time next quarter, and then reenter all the diagrams by hand.   ****   Then, on July 1 another miracle happens! You are done with the design!   Rather than go to your boss and complain, you stock your middle desk drawer with some vodka.   **** They threw a party to celebrate the on-time completion of the design phase and their graduation to CMM level 3. This time, you find BB's speech so stirring that you have to use the restroom before it begins. New banners and plaques are all over your workplace. They show pictures of eagles and mountain climbers, and they talk about teamwork and empowerment. They read better after a few scotches. That reminds you that you need to clear out your file cabinet to make room for the brandy. You and your team begin to code. But you rapidly discover that the design is lacking in some significant areas. Actually, it's lacking any significance at all. You convene a design session in one of the conference rooms to try to work through some of the nastier problems. But your boss catches you at it and disbands the meeting, saying, "The design phase is over. The only allowable activity is coding. Now get back to it."   ****   The code generated by Dandelion is really hideous. It turns out that you and your team were using association and aggregation the wrong way, after all. All the generated code has to be edited to correct these flaws. Editing this code is extremely difficult because it has been instrumented with ugly comment blocks that have special syntax that Dandelion needs in order to keep the diagrams in sync with the code. If you accidentally alter one of these comments, the diagrams will be regenerated incorrectly. It turns out that "Round the Horn Engineering" requires an awful lot of effort. The more you try to keep the code compatible with Dandelion, the more errors Dandelion generates. In the end, you give up and decide to keep the diagrams up to date manually. A second later, you decide that there's no point in keeping the diagrams up to date at all. Besides, who has time?   Your boss hires a consultant to build tools to count the number of lines of code that are being produced. He puts a big thermometer graph on the wall with the number 1,000,000 on the top. Every day, he extends the red line to show how many lines have been added. Three days after the thermometer appears on the wall, your boss stops you in the hall. "That graph isn't growing quickly enough. We need to have a million lines done by October 1." "We aren't even sh-sh-sure that the proshect will require a m-million linezh," you blather. "We have to have a million lines done by October 1," your boss reiterates. His points have grown again, and the Grecian formula he uses on them creates an aura of authority and competence. "Are you sure your comment blocks are big enough?" Then, in a flash of managerial insight, he says, "I have it! I want you to institute a new policy among the engineers. No line of code is to be longer than 20 characters. Any such line must be split into two or more preferably more. All existing code needs to be reworked to this standard. That'll get our line count up!"   You decide not to tell him that this will require two unscheduled work months. You decide not to tell him anything at all. You decide that intravenous injections of pure ethanol are the only solution. You make the appropriate arrangements. Hack, hack, hack, and hack. You and your team madly code away. By August 1, your boss, frowning at the thermometer on the wall, institutes a mandatory 50-hour workweek.   Hack, hack, hack, and hack. By September 1st, the thermometer is at 1.2 million lines and your boss asks you to write a report describing why you exceeded the coding budget by 20 percent. He institutes mandatory Saturdays and demands that the project be brought back down to a million lines. You start a campaign of remerging lines. Hack, hack, hack, and hack. Tempers are flaring; people are quitting; QA is raining trouble reports down on you. Customers are demanding installation and user manuals; salespeople are demanding advance demonstrations for special customers; the requirements document is still thrashing, the marketing folks are complaining that the product isn't anything like they specified, and the liquor store won't accept your credit card anymore. Something has to give.    On September 15, BB calls a meeting. As he enters the room, his points are emitting clouds of steam. When he speaks, the bass overtones of his carefully manicured voice cause the pit of your stomach to roll over. "The QA manager has told me that this project has less than 50 percent of the required features implemented. He has also informed me that the system crashes all the time, yields wrong results, and is hideously slow. He has also complained that he cannot keep up with the continuous train of daily releases, each more buggy than the last!" He stops for a few seconds, visibly trying to compose himself. "The QA manager estimates that, at this rate of development, we won't be able to ship the product until December!" Actually, you think it's more like March, but you don't say anything. "December!" BB roars with such derision that people duck their heads as though he were pointing an assault rifle at them. "December is absolutely out of the question. Team leaders, I want new estimates on my desk in the morning. I am hereby mandating 65-hour work weeks until this project is complete. And it better be complete by November 1."   As he leaves the conference room, he is heard to mutter: "Empowermentbah!" * * * Your boss is bald; his points are mounted on BB's wall. The fluorescent lights reflecting off his pate momentarily dazzle you. "Do you have anything to drink?" he asks. Having just finished your last bottle of Boone's Farm, you pull a bottle of Thunderbird from your bookshelf and pour it into his coffee mug. "What's it going to take to get this project done? " he asks. "We need to freeze the requirements, analyze them, design them, and then implement them," you say callously. "By November 1?" your boss exclaims incredulously. "No way! Just get back to coding the damned thing." He storms out, scratching his vacant head.   A few days later, you find that your boss has been transferred to the corporate research division. Turnover has skyrocketed. Customers, informed at the last minute that their orders cannot be fulfilled on time, have begun to cancel their orders. Marketing is re-evaluating whether this product aligns with the overall goals of the company. Memos fly, heads roll, policies change, and things are, overall, pretty grim. Finally, by March, after far too many sixty-five hour weeks, a very shaky version of the software is ready. In the field, bug-discovery rates are high, and the technical support staff are at their wits' end, trying to cope with the complaints and demands of the irate customers. Nobody is happy.   In April, BB decides to buy his way out of the problem by licensing a product produced by Rupert Industries and redistributing it. The customers are mollified, the marketing folks are smug, and you are laid off.     Rupert Industries: Project Alpha   Your name is Robert. The date is January 3, 2001. The quiet hours spent with your family this holiday have left you refreshed and ready for work. You are sitting in a conference room with your team of professionals. The manager of the division called the meeting. "We have some ideas for a new project," says the division manager. Call him Russ. He is a high-strung British chap with more energy than a fusion reactor. He is ambitious and driven but understands the value of a team. Russ describes the essence of the new market opportunity the company has identified and introduces you to Jane, the marketing manager, who is responsible for defining the products that will address it. Addressing you, Jane says, "We'd like to start defining our first product offering as soon as possible. When can you and your team meet with me?" You reply, "We'll be done with the current iteration of our project this Friday. We can spare a few hours for you between now and then. After that, we'll take a few people from the team and dedicate them to you. We'll begin hiring their replacements and the new people for your team immediately." "Great," says Russ, "but I want you to understand that it is critical that we have something to exhibit at the trade show coming up this July. If we can't be there with something significant, we'll lose the opportunity."   "I understand," you reply. "I don't yet know what it is that you have in mind, but I'm sure we can have something by July. I just can't tell you what that something will be right now. In any case, you and Jane are going to have complete control over what we developers do, so you can rest assured that by July, you'll have the most important things that can be accomplished in that time ready to exhibit."   Russ nods in satisfaction. He knows how this works. Your team has always kept him advised and allowed him to steer their development. He has the utmost confidence that your team will work on the most important things first and will produce a high-quality product.   * * *   "So, Robert," says Jane at their first meeting, "How does your team feel about being split up?" "We'll miss working with each other," you answer, "but some of us were getting pretty tired of that last project and are looking forward to a change. So, what are you people cooking up?" Jane beams. "You know how much trouble our customers currently have . . ." And she spends a half hour or so describing the problem and possible solution. "OK, wait a second" you respond. "I need to be clear about this." And so you and Jane talk about how this system might work. Some of her ideas aren't fully formed. You suggest possible solutions. She likes some of them. You continue discussing.   During the discussion, as each new topic is addressed, Jane writes user story cards. Each card represents something that the new system has to do. The cards accumulate on the table and are spread out in front of you. Both you and Jane point at them, pick them up, and make notes on them as you discuss the stories. The cards are powerful mnemonic devices that you can use to represent complex ideas that are barely formed.   At the end of the meeting, you say, "OK, I've got a general idea of what you want. I'm going to talk to the team about it. I imagine they'll want to run some experiments with various database structures and presentation formats. Next time we meet, it'll be as a group, and we'll start identifying the most important features of the system."   A week later, your nascent team meets with Jane. They spread the existing user story cards out on the table and begin to get into some of the details of the system. The meeting is very dynamic. Jane presents the stories in the order of their importance. There is much discussion about each one. The developers are concerned about keeping the stories small enough to estimate and test. So they continually ask Jane to split one story into several smaller stories. Jane is concerned that each story have a clear business value and priority, so as she splits them, she makes sure that this stays true.   The stories accumulate on the table. Jane writes them, but the developers make notes on them as needed. Nobody tries to capture everything that is said; the cards are not meant to capture everything but are simply reminders of the conversation.   As the developers become more comfortable with the stories, they begin writing estimates on them. These estimates are crude and budgetary, but they give Jane an idea of what the story will cost.   At the end of the meeting, it is clear that many more stories could be discussed. It is also clear that the most important stories have been addressed and that they represent several months worth of work. Jane closes the meeting by taking the cards with her and promising to have a proposal for the first release in the morning.   * * *   The next morning, you reconvene the meeting. Jane chooses five cards and places them on the table. "According to your estimates, these cards represent about one perfect team-week's worth of work. The last iteration of the previous project managed to get one perfect team-week done in 3 real weeks. If we can get these five stories done in 3 weeks, we'll be able to demonstrate them to Russ. That will make him feel very comfortable about our progress." Jane is pushing it. The sheepish look on her face lets you know that she knows it too. You reply, "Jane, this is a new team, working on a new project. It's a bit presumptuous to expect that our velocity will be the same as the previous team's. However, I met with the team yesterday afternoon, and we all agreed that our initial velocity should, in fact, be set to one perfectweek for every 3 real-weeks. So you've lucked out on this one." "Just remember," you continue, "that the story estimates and the story velocity are very tentative at this point. We'll learn more when we plan the iteration and even more when we implement it."   Jane looks over her glasses at you as if to say "Who's the boss around here, anyway?" and then smiles and says, "Yeah, don't worry. I know the drill by now."Jane then puts 15 more cards on the table. She says, "If we can get all these cards done by the end of March, we can turn the system over to our beta test customers. And we'll get good feedback from them."   You reply, "OK, so we've got our first iteration defined, and we have the stories for the next three iterations after that. These four iterations will make our first release."   "So," says Jane, can you really do these five stories in the next 3 weeks?" "I don't know for sure, Jane," you reply. "Let's break them down into tasks and see what we get."   So Jane, you, and your team spend the next several hours taking each of the five stories that Jane chose for the first iteration and breaking them down into small tasks. The developers quickly realize that some of the tasks can be shared between stories and that other tasks have commonalities that can probably be taken advantage of. It is clear that potential designs are popping into the developers' heads. From time to time, they form little discussion knots and scribble UML diagrams on some cards.   Soon, the whiteboard is filled with the tasks that, once completed, will implement the five stories for this iteration. You start the sign-up process by saying, "OK, let's sign up for these tasks." "I'll take the initial database generation." Says Pete. "That's what I did on the last project, and this doesn't look very different. I estimate it at two of my perfect workdays." "OK, well, then, I'll take the login screen," says Joe. "Aw, darn," says Elaine, the junior member of the team, "I've never done a GUI, and kinda wanted to try that one."   "Ah, the impatience of youth," Joe says sagely, with a wink in your direction. "You can assist me with it, young Jedi." To Jane: "I think it'll take me about three of my perfect workdays."   One by one, the developers sign up for tasks and estimate them in terms of their own perfect workdays. Both you and Jane know that it is best to let the developers volunteer for tasks than to assign the tasks to them. You also know full well that you daren't challenge any of the developers' estimates. You know these people, and you trust them. You know that they are going to do the very best they can.   The developers know that they can't sign up for more perfect workdays than they finished in the last iteration they worked on. Once each developer has filled his or her schedule for the iteration, they stop signing up for tasks.   Eventually, all the developers have stopped signing up for tasks. But, of course, tasks are still left on the board.   "I was worried that that might happen," you say, "OK, there's only one thing to do, Jane. We've got too much to do in this iteration. What stories or tasks can we remove?" Jane sighs. She knows that this is the only option. Working overtime at the beginning of a project is insane, and projects where she's tried it have not fared well.   So Jane starts to remove the least-important functionality. "Well, we really don't need the login screen just yet. We can simply start the system in the logged-in state." "Rats!" cries Elaine. "I really wanted to do that." "Patience, grasshopper." says Joe. "Those who wait for the bees to leave the hive will not have lips too swollen to relish the honey." Elaine looks confused. Everyone looks confused. "So . . .," Jane continues, "I think we can also do away with . . ." And so, bit by bit, the list of tasks shrinks. Developers who lose a task sign up for one of the remaining ones.   The negotiation is not painless. Several times, Jane exhibits obvious frustration and impatience. Once, when tensions are especially high, Elaine volunteers, "I'll work extra hard to make up some of the missing time." You are about to correct her when, fortunately, Joe looks her in the eye and says, "When once you proceed down the dark path, forever will it dominate your destiny."   In the end, an iteration acceptable to Jane is reached. It's not what Jane wanted. Indeed, it is significantly less. But it's something the team feels that can be achieved in the next 3 weeks.   And, after all, it still addresses the most important things that Jane wanted in the iteration. "So, Jane," you say when things had quieted down a bit, "when can we expect acceptance tests from you?" Jane sighs. This is the other side of the coin. For every story the development team implements,   Jane must supply a suite of acceptance tests that prove that it works. And the team needs these long before the end of the iteration, since they will certainly point out differences in the way Jane and the developers imagine the system's behaviour.   "I'll get you some example test scripts today," Jane promises. "I'll add to them every day after that. You'll have the entire suite by the middle of the iteration."   * * *   The iteration begins on Monday morning with a flurry of Class, Responsibilities, Collaborators sessions. By midmorning, all the developers have assembled into pairs and are rapidly coding away. "And now, my young apprentice," Joe says to Elaine, "you shall learn the mysteries of test-first design!"   "Wow, that sounds pretty rad," Elaine replies. "How do you do it?" Joe beams. It's clear that he has been anticipating this moment. "OK, what does the code do right now?" "Huh?" replied Elaine, "It doesn't do anything at all; there is no code."   "So, consider our task; can you think of something the code should do?" "Sure," Elaine said with youthful assurance, "First, it should connect to the database." "And thereupon, what must needs be required to connecteth the database?" "You sure talk weird," laughed Elaine. "I think we'd have to get the database object from some registry and call the Connect() method. "Ah, astute young wizard. Thou perceives correctly that we requireth an object within which we can cacheth the database object." "Is 'cacheth' really a word?" "It is when I say it! So, what test can we write that we know the database registry should pass?" Elaine sighs. She knows she'll just have to play along. "We should be able to create a database object and pass it to the registry in a Store() method. And then we should be able to pull it out of the registry with a Get() method and make sure it's the same object." "Oh, well said, my prepubescent sprite!" "Hay!" "So, now, let's write a test function that proves your case." "But shouldn't we write the database object and registry object first?" "Ah, you've much to learn, my young impatient one. Just write the test first." "But it won't even compile!" "Are you sure? What if it did?" "Uh . . ." "Just write the test, Elaine. Trust me." And so Joe, Elaine, and all the other developers began to code their tasks, one test case at a time. The room in which they worked was abuzz with the conversations between the pairs. The murmur was punctuated by an occasional high five when a pair managed to finish a task or a difficult test case.   As development proceeded, the developers changed partners once or twice a day. Each developer got to see what all the others were doing, and so knowledge of the code spread generally throughout the team.   Whenever a pair finished something significant whether a whole task or simply an important part of a task they integrated what they had with the rest of the system. Thus, the code base grew daily, and integration difficulties were minimized.   The developers communicated with Jane on a daily basis. They'd go to her whenever they had a question about the functionality of the system or the interpretation of an acceptance test case.   Jane, good as her word, supplied the team with a steady stream of acceptance test scripts. The team read these carefully and thereby gained a much better understanding of what Jane expected the system to do. By the beginning of the second week, there was enough functionality to demonstrate to Jane. She watched eagerly as the demonstration passed test case after test case. "This is really cool," Jane said as the demonstration finally ended. "But this doesn't seem like one-third of the tasks. Is your velocity slower than anticipated?"   You grimace. You'd been waiting for a good time to mention this to Jane but now she was forcing the issue. "Yes, unfortunately, we are going more slowly than we had expected. The new application server we are using is turning out to be a pain to configure. Also, it takes forever to reboot, and we have to reboot it whenever we make even the slightest change to its configuration."   Jane eyes you with suspicion. The stress of last Monday's negotiations had still not entirely dissipated. She says, "And what does this mean to our schedule? We can't slip it again, we just can't. Russ will have a fit! He'll haul us all into the woodshed and ream us some new ones."   You look Jane right in the eyes. There's no pleasant way to give someone news like this. So you just blurt out, "Look, if things keep going like they're going, we're not going to be done with everything by next Friday. Now it's possible that we'll figure out a way to go faster. But, frankly, I wouldn't depend on that. You should start thinking about one or two tasks that could be removed from the iteration without ruining the demonstration for Russ. Come hell or high water, we are going to give that demonstration on Friday, and I don't think you want us to choose which tasks to omit."   "Aw forchrisakes!" Jane barely manages to stifle yelling that last word as she stalks away, shaking her head. Not for the first time, you say to yourself, "Nobody ever promised me project management would be easy." You are pretty sure it won't be the last time, either.   Actually, things went a bit better than you had hoped. The team did, in fact, have to drop one task from the iteration, but Jane had chosen wisely, and the demonstration for Russ went without a hitch. Russ was not impressed with the progress, but neither was he dismayed. He simply said, "This is pretty good. But remember, we have to be able to demonstrate this system at the trade show in July, and at this rate, it doesn't look like you'll have all that much to show." Jane, whose attitude had improved dramatically with the completion of the iteration, responded to Russ by saying, "Russ, this team is working hard, and well. When July comes around, I am confident that we'll have something significant to demonstrate. It won't be everything, and some of it may be smoke and mirrors, but we'll have something."   Painful though the last iteration was, it had calibrated your velocity numbers. The next iteration went much better. Not because your team got more done than in the last iteration but simply because the team didn't have to remove any tasks or stories in the middle of the iteration.   By the start of the fourth iteration, a natural rhythm has been established. Jane, you, and the team know exactly what to expect from one another. The team is running hard, but the pace is sustainable. You are confident that the team can keep up this pace for a year or more.   The number of surprises in the schedule diminishes to near zero; however, the number of surprises in the requirements does not. Jane and Russ frequently look over the growing system and make recommendations or changes to the existing functionality. But all parties realize that these changes take time and must be scheduled. So the changes do not cause anyone's expectations to be violated. In March, there is a major demonstration of the system to the board of directors. The system is very limited and is not yet in a form good enough to take to the trade show, but progress is steady, and the board is reasonably impressed.   The second release goes even more smoothly than the first. By now, the team has figured out a way to automate Jane's acceptance test scripts. The team has also refactored the design of the system to the point that it is really easy to add new features and change old ones. The second release was done by the end of June and was taken to the trade show. It had less in it than Jane and Russ would have liked, but it did demonstrate the most important features of the system. Although customers at the trade show noticed that certain features were missing, they were very impressed overall. You, Russ, and Jane all returned from the trade show with smiles on your faces. You all felt as though this project was a winner.   Indeed, many months later, you are contacted by Rufus Inc. That company had been working on a system like this for its internal operations. Rufus has canceled the development of that system after a death-march project and is negotiating to license your technology for its environment.   Indeed, things are looking up!

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  • Parallelism in .NET – Part 11, Divide and Conquer via Parallel.Invoke

    - by Reed
    Many algorithms are easily written to work via recursion.  For example, most data-oriented tasks where a tree of data must be processed are much more easily handled by starting at the root, and recursively “walking” the tree.  Some algorithms work this way on flat data structures, such as arrays, as well.  This is a form of divide and conquer: an algorithm design which is based around breaking up a set of work recursively, “dividing” the total work in each recursive step, and “conquering” the work when the remaining work is small enough to be solved easily. Recursive algorithms, especially ones based on a form of divide and conquer, are often a very good candidate for parallelization. This is apparent from a common sense standpoint.  Since we’re dividing up the total work in the algorithm, we have an obvious, built-in partitioning scheme.  Once partitioned, the data can be worked upon independently, so there is good, clean isolation of data. Implementing this type of algorithm is fairly simple.  The Parallel class in .NET 4 includes a method suited for this type of operation: Parallel.Invoke.  This method works by taking any number of delegates defined as an Action, and operating them all in parallel.  The method returns when every delegate has completed: Parallel.Invoke( () => { Console.WriteLine("Action 1 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); }, () => { Console.WriteLine("Action 2 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); }, () => { Console.WriteLine("Action 3 executing in thread {0}", Thread.CurrentThread.ManagedThreadId); } ); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Running this simple example demonstrates the ease of using this method.  For example, on my system, I get three separate thread IDs when running the above code.  By allowing any number of delegates to be executed directly, concurrently, the Parallel.Invoke method provides us an easy way to parallelize any algorithm based on divide and conquer.  We can divide our work in each step, and execute each task in parallel, recursively. For example, suppose we wanted to implement our own quicksort routine.  The quicksort algorithm can be designed based on divide and conquer.  In each iteration, we pick a pivot point, and use that to partition the total array.  We swap the elements around the pivot, then recursively sort the lists on each side of the pivot.  For example, let’s look at this simple, sequential implementation of quicksort: public static void QuickSort<T>(T[] array) where T : IComparable<T> { QuickSortInternal(array, 0, array.Length - 1); } private static void QuickSortInternal<T>(T[] array, int left, int right) where T : IComparable<T> { if (left >= right) { return; } SwapElements(array, left, (left + right) / 2); int last = left; for (int current = left + 1; current <= right; ++current) { if (array[current].CompareTo(array[left]) < 0) { ++last; SwapElements(array, last, current); } } SwapElements(array, left, last); QuickSortInternal(array, left, last - 1); QuickSortInternal(array, last + 1, right); } static void SwapElements<T>(T[] array, int i, int j) { T temp = array[i]; array[i] = array[j]; array[j] = temp; } Here, we implement the quicksort algorithm in a very common, divide and conquer approach.  Running this against the built-in Array.Sort routine shows that we get the exact same answers (although the framework’s sort routine is slightly faster).  On my system, for example, I can use framework’s sort to sort ten million random doubles in about 7.3s, and this implementation takes about 9.3s on average. Looking at this routine, though, there is a clear opportunity to parallelize.  At the end of QuickSortInternal, we recursively call into QuickSortInternal with each partition of the array after the pivot is chosen.  This can be rewritten to use Parallel.Invoke by simply changing it to: // Code above is unchanged... SwapElements(array, left, last); Parallel.Invoke( () => QuickSortInternal(array, left, last - 1), () => QuickSortInternal(array, last + 1, right) ); } This routine will now run in parallel.  When executing, we now see the CPU usage across all cores spike while it executes.  However, there is a significant problem here – by parallelizing this routine, we took it from an execution time of 9.3s to an execution time of approximately 14 seconds!  We’re using more resources as seen in the CPU usage, but the overall result is a dramatic slowdown in overall processing time. This occurs because parallelization adds overhead.  Each time we split this array, we spawn two new tasks to parallelize this algorithm!  This is far, far too many tasks for our cores to operate upon at a single time.  In effect, we’re “over-parallelizing” this routine.  This is a common problem when working with divide and conquer algorithms, and leads to an important observation: When parallelizing a recursive routine, take special care not to add more tasks than necessary to fully utilize your system. This can be done with a few different approaches, in this case.  Typically, the way to handle this is to stop parallelizing the routine at a certain point, and revert back to the serial approach.  Since the first few recursions will all still be parallelized, our “deeper” recursive tasks will be running in parallel, and can take full advantage of the machine.  This also dramatically reduces the overhead added by parallelizing, since we’re only adding overhead for the first few recursive calls.  There are two basic approaches we can take here.  The first approach would be to look at the total work size, and if it’s smaller than a specific threshold, revert to our serial implementation.  In this case, we could just check right-left, and if it’s under a threshold, call the methods directly instead of using Parallel.Invoke. The second approach is to track how “deep” in the “tree” we are currently at, and if we are below some number of levels, stop parallelizing.  This approach is a more general-purpose approach, since it works on routines which parse trees as well as routines working off of a single array, but may not work as well if a poor partitioning strategy is chosen or the tree is not balanced evenly. This can be written very easily.  If we pass a maxDepth parameter into our internal routine, we can restrict the amount of times we parallelize by changing the recursive call to: // Code above is unchanged... SwapElements(array, left, last); if (maxDepth < 1) { QuickSortInternal(array, left, last - 1, maxDepth); QuickSortInternal(array, last + 1, right, maxDepth); } else { --maxDepth; Parallel.Invoke( () => QuickSortInternal(array, left, last - 1, maxDepth), () => QuickSortInternal(array, last + 1, right, maxDepth)); } We no longer allow this to parallelize indefinitely – only to a specific depth, at which time we revert to a serial implementation.  By starting the routine with a maxDepth equal to Environment.ProcessorCount, we can restrict the total amount of parallel operations significantly, but still provide adequate work for each processing core. With this final change, my timings are much better.  On average, I get the following timings: Framework via Array.Sort: 7.3 seconds Serial Quicksort Implementation: 9.3 seconds Naive Parallel Implementation: 14 seconds Parallel Implementation Restricting Depth: 4.7 seconds Finally, we are now faster than the framework’s Array.Sort implementation.

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