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  • switch namespace by if condtion

    - by pascal
    Hi, in my C++ program I have several namespaces that contain several pointers with identical names. I then want a function to choose a namespace according to a parameter. I.e. something like: #include <iostream> namespace ns1{ double x[5]={1,2,3,4,5}; } namespace ns2{ double x[5]={6,7,8,9,10}; } int main(){ int b=1; if(b==1){ using namespace ns1; } if(b==2){ using namespace ns2; } std::cout << x[3] << std::endl; } However, this doesn't work since the compiler complains that x isn't known in that scope. I guess the problem is that "using namespace ..." is only valid within the if-statement. I think that it should be possible to switch namespaces somehow, but cannot find out how... Do you know how to do this without casting all variable separately? int main(){ int b=1; double *x; if(b==1){ x = ns1::x; } if(b==2){ x = ns2::x; } std::cout << x[3] << std::endl; } Cheers, Pascal

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  • Bizarre static_cast trick?

    - by Rob
    While perusing the Qt source code I came across this gem: template <class T> inline T qgraphicsitem_cast(const QGraphicsItem *item) { return int(static_cast<T>(0)->Type) == int(QGraphicsItem::Type) || (item && int(static_cast<T>(0)->Type) == item->type()) ? static_cast<T>(item) : 0; } Notice the static_cast<T>(0)->Type? I've been using C++ for many years but have never seen 0 being used in a static_cast before. What is this code doing and is it safe? Background: If you derive from QGraphicsItem you are meant to declare an unique enum value called Type that and implement a virtual function called type that returns it, e.g.: class Item : public QGraphicsItem { public: enum { Type = MAGIC_NUMBER }; int type() const { return Type; } ... }; You can then do this: QGraphicsItem* item = new Item; ... Item* derivedItem = qgraphicsitem_cast<Item*>(item); This will probably help explain what that static_cast is trying to do.

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  • Java applet wont run

    - by Courtney
    I am trying to get a Java applet to run properly when linked to an HTML page in Dreamweaver CC. I'm new to all this so please bear with me here. First I saved this code to a .java file //Triangle.java import java.awt.*; import java.applet.Applet; public class Triangle extends Applet { public void paint (Graphics g){ int bottomX=80; int bottomY=200; int base=100; int height=100; g.drawLine(bottomX,bottomY,bottomX+base,bottomY); g.drawLine(bottomX+base,bottomY,bottomX+base/2,bottomY-height); g.drawLine(bottomX+base/2,bottomY-height, bottomX,bottomY); } } I then compiled it entering javac Triangle.java After that, I inserted it into a Dreamwever page using: <html> <applet code=Triangle.class width=400 height=400 > </applet> </html> Now when I try and open the page in Chrome I get an error reading: UnsupportedClassVersionError Triangle: Unsupported major.minor version 52.0 This, as I have read, is an issue with using two incompatible Java versions? In my Java Control Panel it says I am using version 1.8.0_20 and my JDK is jdk1.8.0_20. Does anyone see anything super obvious that I am doing wrong here?

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  • IS operator behaving a bit strangely

    - by flockofcode
    1) According to my book, IS operator can check whether expression E (E is type) can be converted to the target type only if E is either a reference conversion, boxing or unboxing. Since in the following example IS doesn’t check for either of the three types of conversion, the code shouldn’t work, but it does: int i=100; if (i is long) //returns true, indicating that conversion is possible l = i; 2) a) B b; A a = new A(); if (a is B) b = (B)a; int i = b.l; class A { public int l = 100; } class B:A { } The above code always causes compile time error “Use of unassigned variable”. If condition a is B evaluates to false, then b won’t be assigned a value, but if condition is true, then it will. And thus by allowing such a code compiler would have no way of knowing whether the usage of b in code following the if statement is valid or not ( due to not knowing whether a is b evaluates to true or false) , but why should it know that? Intsead why couldn’t runtime handle this? b) But if instead we’re dealing with non reference types, then compiler doesn’t complain, even though the code is identical.Why? int i = 100; long l; if (i is long) l = i; thank you

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  • Can a Java HashMap's size() be out of sync with its actual entries' size ?

    - by trix
    I have a Java HashMap called statusCountMap. Calling size() results in 30. But if I count the entries manually, it's 31 This is in one of my TestNG unit tests. These results below are from Eclipse's Display window (type code - highlight - hit Display Result of Evaluating Selected Text). statusCountMap.size() (int) 30 statusCountMap.keySet().size() (int) 30 statusCountMap.values().size() (int) 30 statusCountMap (java.util.HashMap) {40534-INACTIVE=2, 40526-INACTIVE=1, 40528-INACTIVE=1, 40492-INACTIVE=3, 40492-TOTAL=4, 40513-TOTAL=6, 40532-DRAFT=4, 40524-TOTAL=7, 40526-DRAFT=2, 40528-ACTIVE=1, 40524-DRAFT=2, 40515-ACTIVE=1, 40513-DRAFT=4, 40534-DRAFT=1, 40514-TOTAL=3, 40529-DRAFT=4, 40515-TOTAL=3, 40492-ACTIVE=1, 40528-TOTAL=4, 40514-DRAFT=2, 40526-TOTAL=3, 40524-INACTIVE=2, 40515-DRAFT=2, 40514-ACTIVE=1, 40534-TOTAL=3, 40513-ACTIVE=2, 40528-DRAFT=2, 40532-TOTAL=4, 40524-ACTIVE=3, 40529-ACTIVE=1, 40529-TOTAL=5} statusCountMap.entrySet().size() (int) 30 What gives ? Anyone has experienced this ? I'm pretty sure statusCountMap is not being modified at this point. There are 2 methods (lets call them methodA and methodB) that modify statusCountMap concurrently, by repeatedly calling incrementCountInMap. private void incrementCountInMap(Map map, Long id, String qualifier) { String key = id + "-" + qualifier; if (map.get(key) == null) { map.put(key, 0); } synchronized (map) { map.put(key, map.get(key).intValue() + 1); } } methodD is where I'm getting the issue. methodD has a TestNG @dependsOnMethods = { "methodA", "methodB" } so when methodD is executing, statusCountMap is pretty much static already. I'm mentioning this because it might be a bug in TestNG. I'm using Sun JDK 1.6.0_24. TestNG is testng-5.9-jdk15.jar Hmmm ... after rereading my post, could it be because of concurrent execution of outside-of-synchronized-block map.get(key) == null & map.put(key,0) that's causing this issue ?

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  • Can a member struct be zero-init from the constructor initializer list without calling memset?

    - by selbie
    Let's say I have the following structure declaration (simple struct with no constructor). struct Foo { int x; int y; int z; char szData[DATA_SIZE]; }; Now let's say this struct is a member of a C++ class as follows: class CFoobar { Foo _foo; public: CFoobar(); }; If I declare CFoobar's constructor as follows: CFoobar::CFoobar() { printf("_foo = {%d, %d, %d}\n", _foo.x, _foo.y,_foo.z); for (int x = 0; x < 100; x++) printf("%d\n", _foo.szData[x]); } As you would expect, when CFoobar's constructor runs, garbage data gets printed out Obviously, the easy fix is to memset or ZeroMemory &_foo. It's what I've always done... However, I did notice that if add _foo to the constructor's initialization list with no parameters as follows: CFoobar::CFoobar() : _foo() { That this appears to zero-out the member variables of _foo. At least that was the case with g++ on linux. Now here's my question: Is this standard C++, or is this compiler specific behavior? If it's standard behavior, can someone quote me a reference from an official source? Any "gotchas" in regards to implicit zero-init behavior with more complicated structs and classes?

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  • Using new (this) to reuse constructors

    - by Brandon Bodnar
    This came up recently in a class for which I am a teaching assistant. We were teaching the students how to do copy constructors in c++, and the students who were originally taught java asked if you can call one constructor from another. I know the answer to this is no, as they are using the pedantic flag for their code in class, and the old standards do not have support for this. I found on Stackoverflow and other sites a suggestion to fake this using new (this) such as follows class MyClass { private: int * storedValue; public: MyClass(int initialValue = 0) { storedValue = new int(initialValue); } ~ MyClass() { delete storedValue; } MyClass(const MyClass &b) { new (this) MyClass(*(b.storedValue)); } int value() { return *storedValue; } }; This is really simple code, and obviously does not save any code by reusing the constructor, but it is just for example. My question is if this is even standard compliant, and if there are any edge cases that should be considered that would prevent this from being sound code?

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  • Saving image to server with php

    - by salmon
    Hey i have the following script, basicaly a flash file sends it some data and it creates a image and then opens a save as dialog box for the user so that they can save the image to there system.Here the problem comes in, how would i go about also saving the image to my server? <?php $to = $_POST['to']; $from = $_POST['from']; $fname = $_POST['fname']; $send = $_POST['send']; $data = explode(",", $_POST['img']); $width = $_POST['width']; $height = $_POST['height']; $image=imagecreatetruecolor( $width ,$height ); $background = imagecolorallocate( $image ,0 , 0 , 0 ); //Copy pixels $i = 0; for($x=0; $x<=$width; $x++){ for($y=0; $y<=$height; $y++){ $int = hexdec($data[$i++]); $color = ImageColorAllocate ($image, 0xFF & ($int >> 0x10), 0xFF & ($int >> 0x8), 0xFF & $int); imagesetpixel ( $image , $x , $y , $color ); } } //Output image and clean #header("Content-Disposition: attachment; filename=test.jpg" ); header("Content-type: image/jpeg"); ImageJPEG( $image ); imagedestroy( $image ); ?> Help would be greatly appreciated!

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  • "pseudo-atomic" operations in C++

    - by dan
    So I'm aware that nothing is atomic in C++. But I'm trying to figure out if there are any "pseudo-atomic" assumptions I can make. The reason is that I want to avoid using mutexes in some simple situations where I only need very weak guarantees. 1) Suppose I have globally defined volatile bool b, which initially I set true. Then I launch a thread which executes a loop while(b) doSomething(); Meanwhile, in another thread, I execute b=true. Can I assume that the first thread will continue to execute? In other words, if b starts out as true, and the first thread checks the value of b at the same time as the second thread assigns b=true, can I assume that the first thread will read the value of b as true? Or is it possible that at some intermediate point of the assignment b=true, the value of b might be read as false? 2) Now suppose that b is initially false. Then the first thread executes bool b1=b; bool b2=b; if(b1 && !b2) bad(); while the second thread executes b=true. Can I assume that bad() never gets called? 3) What about an int or other builtin types: suppose I have volatile int i, which is initially (say) 7, and then I assign i=7. Can I assume that, at any time during this operation, from any thread, the value of i will be equal to 7? 4) I have volatile int i=7, and then I execute i++ from some thread, and all other threads only read the value of i. Can I assume that i never has any value, in any thread, except for either 7 or 8? 5) I have volatile int i, from one thread I execute i=7, and from another I execute i=8. Afterwards, is i guaranteed to be either 7 or 8 (or whatever two values I have chosen to assign)?

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  • copy rows with special condition

    - by pooria_googooli
    I have a table with a lot of columns. For example I have a table with these columns : ID,Fname,Lname,Tel,Mob,Email,Job,Code,Company,...... ID column is auto number column. I want to copy all rows in this table to this table and change the company column value to 12 in this copied row. I don't want to write name all of the columns because I have a lot of table with a lot of columns. I tried this code but I had this error : declare @c int; declare @i int; select * into CmDet from CmDet; select @C= count(id) from CmDet; while @i < @C begin UPDATE CmDet SET company =12 WHERE company=11 set @i += 1 end error : Msg 2714, Level 16, State 6, Line 3 There is already an object named 'CmDet' in the database. I changed the code to this declare @c int declare @i int insert into CmDet select * from CmDet; select @C= count(id) from CmDet; while @i < @C begin UPDATE CmDet SET company =12 WHERE company=11 set @i += 1 end and I had this error : Msg 8101, Level 16, State 1, Line 3 An explicit value for the identity column in table 'CmDet' can only be specified when a column list is used and IDENTITY_INSERT is ON. What should I do ?

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  • Storing Number in an integer from sql Database

    - by ar31an
    i am using database with table RESUME and column PageIndex in it which type is number in database but when i want to store this PageIndex value to an integer i get exception error Specified cast is not valid. here is the code string sql; string conString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=D:\\Deliverable4.accdb"; protected OleDbConnection rMSConnection; protected OleDbDataAdapter rMSDataAdapter; protected DataSet dataSet; protected DataTable dataTable; protected DataRow dataRow; on Button Click sql = "select PageIndex from RESUME"; rMSConnection = new OleDbConnection(conString); rMSDataAdapter = new OleDbDataAdapter(sql, rMSConnection); dataSet = new DataSet("pInDex"); rMSDataAdapter.Fill(dataSet, "RESUME"); dataTable = dataSet.Tables["RESUME"]; int pIndex = (int)dataTable.Rows[0][0]; rMSConnection.Close(); if (pIndex == 0) { Response.Redirect("Create Resume-1.aspx"); } else if (pIndex == 1) { Response.Redirect("Create Resume-2.aspx"); } else if (pIndex == 2) { Response.Redirect("Create Resume-3.aspx"); } } i am getting error in this line int pIndex = (int)dataTable.Rows[0][0];

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  • How can a B-tree node be represented?

    - by chronodekar
    We're learning B-trees in class and have been asked to implement them in code. The teacher has left choice of programming language to us and I want to try and do it in C#. My problem is that the following structure is illegal in C#, unsafe struct BtreeNode { int key_num; // The number of keys in a node int[] key; // Array of keys bool leaf; // Is it a leaf node or not? BtreeNode*[] c; // Pointers to next nodes } Specifically, one is not allowed to create a pointer to point to the structure itself. Is there some work-around or alternate approach I could use? I'm fairly certain that there MUST be a way to do this within the managed code, but I can't figure it out. EDIT: Eric's answer pointed me in the right direction. Here's what I ended up using, class BtreeNode { public List<BtreeNode> children; // The child nodes public static int MinDeg; // The Minimum Degree of the tree public bool IsLeaf { get; set; } // Is the current node a leaf or not? public List<int> key; // The list of keys ... }

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  • Java Swing: How to add a CellRenderer for displaying a Date?

    - by HansDampf
    I have a Table: public class AppointmentTableModel extends AbstractTableModel { private int columns; private int rows; ArrayList<Appointment> appointments;... So each row of the table contains one Appointment. public class Appointment { private Date date; private Sample sample; private String comment; private ArrayList<Action> history; public Appointment(Date date, Sample sample, String comment) { this.date = date; this.sample = sample; this.comment = comment; this.history = new ArrayList<Action>(); } public Object getByColumn(int columnIndex) { switch (columnIndex) { case 0: return date;//Date: dd:mm:yyyy case 1: return date;//Time mm:hh case 2: return sample;//sample.getID() int (sampleID) case 3: return sample;//sample.getNumber string (telephone number) case 4: return sample;//sample.getName string (name of the person) case 5: return history;//newst element in history as a string case 6: return comment;//comment as string } return null; I added in comments what this one is going to mean. How would I create CellRenderers to display it like this. table.getColumnModel().getColumn(1).setCellRenderer(new DateRenderer()); I also want to add the whole row to be painted in red when the date is later then the current date. And then another column that holds a JButton to open up another screen with the corresponding Appointment as parameter.

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  • Project Euler #119 Make Faster

    - by gangqinlaohu
    Trying to solve Project Euler problem 119: The number 512 is interesting because it is equal to the sum of its digits raised to some power: 5 + 1 + 2 = 8, and 8^3 = 512. Another example of a number with this property is 614656 = 28^4. We shall define an to be the nth term of this sequence and insist that a number must contain at least two digits to have a sum. You are given that a2 = 512 and a10 = 614656. Find a30. Question: Is there a more efficient way to find the answer than just checking every number until a30 is found? My Code int currentNum = 0; long value = 0; for (long a = 11; currentNum != 30; a++){ //maybe a++ is inefficient int test = Util.sumDigits(a); if (isPower(a, test)) { currentNum++; value = a; System.out.println(value + ":" + currentNum); } } System.out.println(value); isPower checks if a is a power of test. Util.sumDigits: public static int sumDigits(long n){ int sum = 0; String s = "" + n; while (!s.equals("")){ sum += Integer.parseInt("" + s.charAt(0)); s = s.substring(1); } return sum; } program has been running for about 30 minutes (might be overflow on the long). Output (so far): 81:1 512:2 2401:3 4913:4 5832:5 17576:6 19683:7 234256:8 390625:9 614656:10 1679616:11 17210368:12 34012224:13 52521875:14 60466176:15 205962976:16 612220032:17

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  • EF Code First, how can I achieve two foreign keys from one table to other table?

    - by Yoo Matsuo
    I've recently downloaded Entity Framework Code First CTP5, and have a trouble with this scenario. I have two tables as follows: Members table ID Name Comments table ID Comment CommentedMemberID CommentMemberID And, the data should be like the following: Members ID Name 1 Mike 2 John 3 Tom Comments ID Comment CommentedMemberID CommentMemberID 1 Good 1 2 2 Good 1 3 3 Bad 2 1 Then, I coded as shown below: public class Member { public int ID {get; set; } public string Name { get; set;} public virtual ICollection Comments { get; set;} } public class Comment { public int ID { get; set; } public string Comment { get; set; } public int CommentedMemberID { get; set; } public int CommentMemberID{ get; set; } public virtual Member CommentedMember { get; set; } public virtual Member CommentMember { get; set; } } public class TestContext : DbContext { public DbSet Members { get; set; } public DbSet Comments { get; set; } } But when I run these models on my cshtml, it gives me errors saying "Cannot create CommentMember instance" or something like that (Sorry, I already changed my models to proceed the EF Code First evaluation, so can't reproduce the same error). I've also tried to use OnModelCreating on the TestContext, but can't find any good instructions and don't know what to do. I saw a blog post of the EF Code First CTP3, and it seems there was a RelatedTo attribute in that version, but now it has gone. Could anyone know how to get it work properly? Or is this a totally wrong way to go with this scenario? Thanks, Yoo

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  • A question on getting number of nodes in a Binary Tree

    - by Robert
    Dear all, I have written up two functions (pseudo code) for calculation the number of nodes and the tree height of a Binary Tree,given the root of the tree. Most importantly,the Binary Tree is represented as the First chiled/next sibling format. so struct TreeNode { Object element; TreeNode *firstChild; TreeNode *nextSibling; } Calculate the # of nodes: public int countNode(TreeNode root) { int count=0; while(root!=null) { root= root.firstChild; count++; } return count; } public int countHeight(TreeNode root) { int height=0; while(root!=null) { root= root.nextSibling; height++; } return height; } This is one of the problem I saw on an algorithm book,and my solution above seems to have some problems,also I didn't quite get the points of using this First Child/right sibling representation of Binary Tree,could you guys give me some idea and feedback,please? Cheers!

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  • implementing interface

    - by 1ace1
    hello guys so i have this assignment that i need to implement interface to go over an ArrayList and sort it (ascending or descnding).I dont want "the" answer i just need some suggestions on my approach and why i get this error Exception in thread "main" java.lang.ClassCastException: Week7.Check cannot be cast to java.lang.Comparable at java.util.Arrays.mergeSort(Unknown Source) at java.util.Arrays.sort(Unknown Source) at java.util.Collections.sort(Unknown Source) at Week7.TestCheck.main(TestCheck.java:18) This is how i did it: comparable had one method called public int compairTo(Object o) public class Check implements comparable { private Integer checkNumber; public Check(Integer newCheckNumber) { setCheckNumber(newCheckNumber); } public String toString() { return getCheckNumber().toString(); } public void setCheckNumber(Integer checkNumber) { this.checkNumber = checkNumber; } public Integer getCheckNumber() { return checkNumber; } @Override public int compairTo(Object o) { Check compair = (Check)o; int result = 0; if (this.getCheckNumber() > compair.getCheckNumber()) result = 1; else if(this.getCheckNumber() < compair.getCheckNumber()) result = -1; return result; } } in my main i had this import java.util.ArrayList; import java.util.Collections; public class TestCheck { public static void main(String[] args) { ArrayList checkList = new ArrayList(); checkList.add(new Check(445)); checkList.add(new Check(101)); checkList.add(new Check(110)); checkList.add(new Check(553)); checkList.add(new Check(123)); Collections.sort(checkList); for (int i =0; i < checkList.size(); i++){ System.out.println(checkList.get(i)); } } }

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  • how to tune BufferedInputStream read()?

    - by technomax
    I am reading a BLOB column from a Oracle database, then writing it to a file as follows: public static int execute(String filename, BLOB blob) { int success = 1; try { File blobFile = new File(filename); FileOutputStream outStream = new FileOutputStream(blobFile); BufferedInputStream inStream = new BufferedInputStream(blob.getBinaryStream()); int length = -1; int size = blob.getBufferSize(); byte[] buffer = new byte[size]; while ((length = inStream.read(buffer)) != -1) { outStream.write(buffer, 0, length); outStream.flush(); } inStream.close(); outStream.close(); } catch (Exception e) { e.printStackTrace(); System.out.println("ERROR(img_exportBlob) Unable to export:"+filename); success = 0; } } The file size is around 3MB and it takes 40-50s to read the buffer. Its actually a 3D image data. So, is there any way by which I can reduce this time?

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  • How to get the parameter names of an object's constructors (reflection)?

    - by Tom
    Say I somehow got an object reference from an other class: Object myObj = anObject; Now I can get the class of this object: Class objClass = myObj.getClass(); Now, I can get all constructors of this class: Constructor[] constructors = objClass.getConstructors(); Now, I can loop every constructor: if (constructors.length > 0) { for (int i = 0; i < constructors.length; i++) { System.out.println(constructors[i]); } } This is already giving me a good summary of the constructor, for example a constructor public Test(String paramName) is shown as public Test(java.lang.String) Instead of giving me the class type however, I want to get the name of the parameter.. in this case "paramName". How would I do that? I tried the following without success: if (constructors.length > 0) { for (int iCon = 0; iCon < constructors.length; iCon++) { Class[] params = constructors[iCon].getParameterTypes(); if (params.length > 0) { for (int iPar = 0; iPar < params.length; iPar++) { Field fields[] = params[iPar].getDeclaredFields(); for (int iFields = 0; iFields < fields.length; iFields++) { String fieldName = fields[i].getName(); System.out.println(fieldName); } } } } } Unfortunately, this is not giving me the expected result. Could anyone tell me how I should do this or what I am doing wrong? Thanks!

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  • lock statement not working when there is a loop inside it?

    - by Ngu Soon Hui
    See this code: public class multiply { public Thread myThread; public int Counter { get; private set; } public string name { get; private set; } public void RunConsolePrint() { lock(this) { RunLockCode("lock"); } } private void RunLockCode(string lockCode) { Console.WriteLine("Now thread "+lockCode+" " + name + " has started"); for (int i = 1; i <= Counter; i++) { Console.WriteLine(lockCode+" "+name + ": count has reached " + i + ": total count is " + Counter); } Console.WriteLine("Thread " + lockCode + " " + name + " has finished"); } public multiply(string pname, int pCounter) { name = pname; Counter = pCounter; myThread = new Thread(new ThreadStart(RunConsolePrint)); } } And this is the test run code: static void Main(string[] args) { int counter = 50; multiply m2 = new multiply("Second", counter); multiply m1 = new multiply("First", counter); m1.myThread.Start(); m2.myThread.Start(); Console.ReadLine(); } I would expect that m2 must execute from start to finish before m1 starts executing, or vice versa, because of the lock statement. But the result I found was the call to lock first and lock second was intermingled together, i.e., something like this Now thread lock First has started Now thread lock Second has started lock First: Count has reached 1: total count is 50 lock First: Count has reached 2: total count is 50 lock Second: Count has reached 1: total count is 50 What did I do wrong?

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  • Adding functions to Java class libraries

    - by Eric
    I'm using a Java class library that is in many ways incomplete: there are many classes that I feel ought to have additional member functions built in. However, I am unsure of the best practice of adding these member functions. Lets call the insufficient base class A. class A { public A(/*long arbitrary arguments*/) { //... } public A(/*long even more arbitrary arguments*/) { //... } public int func() { return 1; } } Ideally, I would like to add a function to A. However, I can't do that. My choice is between: class B extends A { //Implement ALL of A's constructors here public int reallyUsefulFunction() { return func()+1; } } and class AddedFuncs { public int reallyUsefulFunction(A a) { return a.func()+1; } } The way I see it, they both have advantages and disadvantages. The first choice gives a cleaner syntax than the second, and is more logical, but has problems: Let's say I have a third class, C, within the class library. class C { public A func() { return new A(/*...*/); } } As I see it, there is no easy way of doing this: C c; int useful = c.func().reallyUsefulFunction(); as the type returned by C.func() is an A, not a B, and you can't down-cast. So what is the best way of adding a member function to a read-only library class?

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  • Input In Java- How does it work?

    - by Nir Avnon
    Hey guys, with a lot of help from you i was managed to write this nice code (I'm new in it, so kind of exciting.. :) ) And still I have not understand how can I input this code. first of all, I get an this error in the console line (I'm using Eclipse): Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at NumberConverter.main(NumberConverter.java:5). What does that mean? I just want to chack whether it works, and I can't call the function/program any how. I used to call in an "old fashion way", like in scheme, to the function that I wrote and see if something happens. How does it work in java? Do we call the program itself? function? what and where do we write? -I want to chack if it works, doesn't matter how, and I'll be glad to know how can I plugin input. Thank you so much! public class NumberConverter{ public static void main(String[] args) { int i = Integer.parseInt(args[0]); toBinary(i); toOctal(i); toHex(i); } public static void toBinary(int int1){ System.out.println(int1 + " in binary is"); System.out.println(Integer.toBinaryString(int1)); } public static void toOctal(int int1){ System.out.println(int1 + " in octal is"); System.out.println(Integer.toOctalString(int1)); } public static void toHex(int int1){ System.out.println(int1 + " in hex is"); System.out.println(Integer.toHexString(int1)); } }

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  • Equvalent c++0x program withought using boost threads..

    - by Eternal Learner
    I have the below simple program using boost threads, what would be the changes needed to do the same in c++0X #include<iostream> #include<boost/thread/thread.hpp> boost::mutex mutex; struct count { count(int i): id(i){} void operator()() { boost::mutex::scoped_lock lk(mutex); for(int i = 0 ; i < 10000 ; i++) { std::cout<<"Thread "<<id<<"has been called "<<i<<" Times"<<std::endl; } } private: int id; }; int main() { boost::thread thr1(count(1)); boost::thread thr2(count(2)); boost::thread thr3(count(3)); thr1.join(); thr2.join(); thr3.join(); return 0; }

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  • C++ - my loop keeps on adding up to 0

    - by user1756913
    so far here's my code #include <iostream> using namespace std; int main () { int num1 = 0; int num2 = 0; int sum = 0; for(num2 = num1; num1 <= num2; num1 +=2) sum += num1; num1 = num1 / 2 == 0? num1 : num1 + 1; num2 = num2 / 2 == 0? num2 : num2 - 1; cout << "Enter the First Number:" << endl; cin >> num1; cout << "Enter the Second Number:" << endl; cin >> num2; cout << "Total Sum: " << sum << endl; } //end for but the sum keeps on adding up to 0 :/ here's the problem. Create a program that displays the sum of the even numbers between and including two numbers entered by the user. In other words, if the user enters an even number, that number should be included in the sum. For example, if the user enters the integers 2 and 7, the sum is 12 (2 + 4 + 6). If the user enters the integers 2 and 8, the sum is 20 (2 + 4 + 6 + 8 ). Display an error message if the first integer entered by the user is greater than the second integer.

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  • Output error in comparing characters from two strings

    - by Andrew Martin
    I'm stuck with my a piece of code I'm creating. My IDE is Eclipse and when I use its debugging feature, to trace what's happening on each line, it outputs perfectly. However, when I click the "run" project, it just outputs a blank screen: public static void compareInterests(Client[] clientDetails) { int interests = 0; for (int p = 0; p < numberOfClients; p++) { for (int q = 0; q < numberOfClients; q++) { String a = clientDetails[p].getClientInterests(); String b = clientDetails[q].getClientInterests(); int count = 0; while (count < a.length()) { if (a.charAt(count) == b.charAt(count)) interests++; count++; } if ((interests >= 3) && (clientDetails[p].getClientName() != clientDetails[q].getClientName())) System.out.print (clientDetails[p].getClientName() + " is compatible with " + clientDetails[q].getClientName()); interests = 0; } } } The code is designed to import an object array which contains information on a client's name and a client's interests. The client's interests are stored in the format "01010", where each 1 means they are interested in that activity, each 0 means they are not. My code compares each character of every client's string with every other client's string and outputs the results for all client's that don't have the same name and have three or more interests in common. When I run this code through Java's debugger, it outputs fine - but when I click run project or compile, I just get a blank screen. Any ideas?

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