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  • Mathematics errors in basic C++ program

    - by H Bomb1013
    I am working with a basic C++ program to determine the area and perimeter of a rectangle. My program works fine for whole numbers but falls apart when I use any number with a decimal. I get the impression that I am leaving something out, but since I'm a complete beginner, I have no idea what. Below is the source: #include <iostream> using namespace std; int main() { // Declared variables int length; // declares variable for length int width; // declares variable for width int area; // declares variable for area int perimeter; // declares variable for perimeter // Statements cout << "Enter the length and the width of the rectangle: "; // states what information to enter cin >> length >> width; // user input of length and width cout << endl; // closes the input area = length * width; // calculates area of rectangle perimeter = 2 * (length + width); //calculates perimeter of rectangle cout << "The area of the rectangle = " << area << " square units." <<endl; // displays the calculation of the area cout << "The perimeter of the rectangle = " << perimeter << " units." << endl; // displays the calculation of the perimeter system ("pause"); // REMOVE BEFORE RELEASE - testing purposes only return 0; }

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  • How to efficiently get highest & lowest values from a List<double?>, and then modify them?

    - by DaveDev
    I have to get the sum of a list of doubles. If the sum is 100, I have to decrement from the highest number until it's = 100. If the sum is < 100, I have to increment the lowest number until it's = 100. I can do this by looping though the list, assigning the values to placeholder variables and testing which is higher or lower but I'm wondering if any gurus out there could suggest a super cool & efficient way to do this? The code below basically outlines what I'm trying to achieve: var splitValues = new List<double?>(); splitValues.Add(Math.Round(assetSplit.EquityTypeSplit() ?? 0)); splitValues.Add(Math.Round(assetSplit.PropertyTypeSplit() ?? 0)); splitValues.Add(Math.Round(assetSplit.FixedInterestTypeSplit() ?? 0)); splitValues.Add(Math.Round(assetSplit.CashTypeSplit() ?? 0)); var listSum = splitValues.Sum(split => split.Value); if (listSum != 100) { if (listSum > 100) { // how to get highest value and decrement by 1 until listSum == 100 // then reassign back into the splitValues list? var highest = // ?? } else { // how to get lowest where value is > 0, and increment by 1 until listSum == 100 // then reassign back into the splitValues list? var lowest = // ?? } } update: the list has to remain in the same order as the items are added.

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  • Persisting object changes from child form to parent form based on button press.

    - by Shyran
    I have created a form that is used for both adding and editing a custom object. Which mode the form takes is provided by an enum value passed from the calling code. I also pass in an object of the custom type. All of my controls at data bound to the specific properties of the custom object. When the form is in Add mode, this works great as when the controls are updated with data, the underlying object is as well. However, in Edit mode, I keep two variables of the custom object supplied by the calling code, the original, and a temporary one made through deep copying. The controls are then bound to the temporary copy, this makes it easy to discard the changes if the user clicks the Cancel button. What I want to know is how to persist those changes back to the original object if the user clicks the OK button, since there is now a disconnect because of the deep copying. I am trying to avoid implementing a internal property on the Add/Edit form if I can. Below is an example of my code: public AddEditCustomerDialog(Customer customer, DialogMode mode) { InitializeComponent(); InitializeCustomer(customer, mode); } private void InitializeCustomer(Customer customer, DialogMode mode) { this.customer = customer; if (mode == DialogMode.Edit) { this.Text = "Edit Customer"; this.tempCustomer = ObjectCopyHelper.DeepCopy(this.customer); this.customerListBindingSource.DataSource = this.tempCustomer; this.phoneListBindingSource.DataSource = this.tempCustomer.PhoneList; } else { this.customerListBindingSource.DataSource = this.customer; this.phoneListBindingSource.DataSource = this.customer.PhoneList; } }

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  • Could someone help me debug my app (not very big)?

    - by Alex
    Not sure if this kind of help is accepted to ask for here, tell me if it isn't. It has to get done before tomorrow, it's not entirerly finished but it should work somewhat ok by now. I'm trying to use the Eclipse debugger (not very used to it). I have my top-level or main class, which is Game, in which I have a constructor and a main method. In the main method I create a new "Game", initiating the constructor. public static void main(String[] args){ Game chess = new Game(); } public Game(){ Board board = new Board(); That's the first thing the debugger reacts to: Thread [main] (Suspended) ClassNotFoundException(Object).<init>() line: 20 [local variables unavailable] ClassNotFoundException(Throwable).<init>(String, Throwable) line: 217 ClassNotFoundException(Exception).<init>(String, Throwable) line: not available ClassNotFoundException.<init>(String) line: not available URLClassLoader$1.run() line: not available AccessController.doPrivileged(PrivilegedExceptionAction<T>, AccessControlContext) line: not available [native method] Launcher$ExtClassLoader(URLClassLoader).findClass(String) line: not available Launcher$ExtClassLoader.findClass(String) line: not available Launcher$ExtClassLoader(ClassLoader).loadClass(String, boolean) line: not available Launcher$AppClassLoader(ClassLoader).loadClass(String, boolean) line: not available Launcher$AppClassLoader.loadClass(String, boolean) line: not available Launcher$AppClassLoader(ClassLoader).loadClass(String) line: not available Game.<init>() line: 15 Game.main(String[]) line: 11 Line 11 is the one line in my main method, line 15 is the instantiation of "board".

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  • PHP Multi-Domain Sessions; ini_set Not Working?

    - by SumWon
    Hello, I'm trying to set it up so if you log in to my website the session carries over to all sub-domains of my website. For example, if you go to domain.com and log in, then go to sub.domain.com, you'll already be logged in at sub.domain.com. To my understanding, you would want to use ini_set('session.cookie_domain','.domain.com') and then session_start(), then set your session variables, but this isn't working. Example of what I'm doing: Code for domain.com: <?php ini_set('session.cookie_domain','.domain.com'); session_start(); $_SESSION['variable'] = 1; ?> Code for sub.domain.com: <?php session_start(); echo $_SESSION['variable']; ?> But $_SESSION['variable'] isn't set. I've also tried using ini_set() in the sub.domain.com code, but it made no difference. I've verified that setting session.cookie_domain is working by using ini_get(). What am I doing wrong? Thanks!

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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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  • Hiding Url for asp.net page

    - by user204588
    Hello, I'm creating an html page that is posted to another page for processing. I don't want users to see the weird URL they are redirected to and I was using FRAMES but I can't figure out how to add my HTML page dynamically because I need the variables and either add frames or try another way to accomplish this. So, based on how I'm creating the page below, how can I hide the URL and add something that I want. Here is how I'm creating the page. StringBuilder sb = new StringBuilder(); sb.Append("<html><head></head>"); sb.Append("<body onload=\"document.frmLaunch.submit();\">"); sb.Append("<form name=\"frmLaunch\" action=\"" + variableTargetURL + "\" method=\"post\">"); sb.Append("<input type=hidden name=\"testVariable\" value=\"" + variableTest + "\">"); sb.Append("</form>"); sb.Append("</body></html>"); HttpResponse response = HttpContext.Current.Response; response.Clear(); response.Write(sb.ToString()); response.End();

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  • Assistance with CC Processing script

    - by JM4
    I am currently implementing a credit card processing script, most as provided by the merchant gateway. The code calls functions within a class and returns a string based on the response. The end php code I am using (details removed of course) with example information is: <?php $gw = new gwapi; $gw->setLogin("username", "password"); $gw->setBilling("John","Smith","Acme, Inc.","888","Suite 200", "Beverly Hills", "CA","77777","US","555-555-5555","555-555-5556","[email protected]", "www.example.com"); // "CA","90210","US","[email protected]"); $gw->setOrder("1234","Big Order",1, 2, "PO1234","65.192.14.10"); $r = $gw->doSale("1.00","4111111111111111","1010"); print $gw->responses['responsetext']; ?> where setlogin allows me to login, setbilling takes the sample consumer information, set order takes the order id and description, dosale takes the amount charged, cc number and exp date. when all the variables are sent validated then sent off for processing, a string is returned in the following format: response=1&responsetext=SUCCESS&authcode=123456&transactionid=23456&avsresponse=M&orderid=&type=sale&response_code=100 where: response = transaction approved or declined response text = textual response authcode = transaction authorization code transactionid = payment gateway tran id avsresponse = avs response code orderid = original order id passed in tran request response_code = numeric mapping of processor response I am trying to solve for the following: How do I take the data which is passed back and display it appropriately on the page - If the transaction failed or AVS code doesnt match my liking or something is wrong, an error is displayed to the consumer; if the transaction processed, they are taken to a completion page and the transaction id is sent in SESSION as output to the consumer If the response_code value matches a table of values, certain actions are taken, i.e. if code =100, take to success page, if code = 300 print specific error on original page to customer, etc.

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  • Overwriting a range of bits in an integer in a generic way

    - by porgarmingduod
    Given two integers X and Y, I want to overwrite bits at position P to P+N. Example: int x = 0xAAAA; // 0b1010101010101010 int y = 0x0C30; // 0b0000110000110000 int result = 0xAC3A; // 0b1010110000111010 Does this procedure have a name? If I have masks, the operation is easy enough: int mask_x = 0xF00F; // 0b1111000000001111 int mask_y = 0x0FF0; // 0b0000111111110000 int result = (x & mask_x) | (y & mask_y); What I can't quite figure out is how to write it in a generic way, such as in the following generic C++ function: template<typename IntType> IntType OverwriteBits(IntType dst, IntType src, int pos, int len) { // If: // dst = 0xAAAA; // 0b1010101010101010 // src = 0x0C30; // 0b0000110000110000 // pos = 4 ^ // len = 8 ^------- // Then: // result = 0xAC3A; // 0b1010110000111010 } The problem is that I cannot figure out how to make the masks properly when all the variables, including the width of the integer, is variable. Does anyone know how to write the above function properly?

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  • Android - update widget text

    - by david
    Hi, i have 2 questions about widgets update I have 2 buttons and i need to change one button text when i press the other one, how can i do this? The first time i open the widget it calls the onUpdate method, but it never calls it again. I need to update the widget every 2 seconds and i have this line in the xml. android:updatePeriodMillis="2000" Do i need a service or should it works just with the updatePeriodMillis tag? onUpdate method RemoteViews views = new RemoteViews(context.getPackageName(), R.layout.newswidget); Intent intent = new Intent(context, DetalleConsulta.class); intent.putExtra(DetalleConsulta.CONSULTA_ID_NAME, "3"); PendingIntent pendingIntent = PendingIntent.getActivity(context, 0, intent, 0); views.setOnClickPendingIntent(R.id.btNews, pendingIntent); /* Inicializa variables para llamar el controlador */ this.imei = ((TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE)).getDeviceId(); this.controlador = new Controlador(this.imei); try { this.respuestas = this.controlador.recuperarNuevasRespuestas(); if(this.respuestas != null &amp;&amp; this.respuestas.size() &gt; 0){ Iterator&lt;Consulta&gt; iterRespuestas = this.respuestas.iterator(); views.setTextViewText(R.id.btNews, ((Consulta)iterRespuestas.next()).getRespuesta()); } } catch (PersistenciaException e) { //TODO manejar error } appWidgetManager.updateAppWidget(appWidgetIds, views); thx a lot!!!

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  • c++ code cons/pros

    - by VirusEcks
    below i have a code that runs in most of my simple programs .. . i want to know if it's good/bad ... and cons/pros . . win32 header file: win32.h #include <windows.h> #include <process.h> #include <stdarg.h> main header file: inc.h #include "win32.h" #ifndef INCS #define INCS #define DD #else #define DD extern #endif #ifndef VARS #define titlen L"my program" #endif DD wchar_t gtitle[512]; DD wchar_t gclass[512]; DD wchar_t gdir[32767]; #include "resources.h" #include "commonfunctions.h" then all files have something like this commonfunctions.h DD inline bool icmp( const char *String1, const char *String2 ) { if ( _stricmp( String1, String2 ) == 0 ) { return true; } return false; } DD inline bool scmp( const char *String1, const char *String2 ) { if ( strcmp( String1, String2 ) == 0 ) { return true; } return false; } all global variables have DD infront of them and all functions have DD too . is there a bad side of this ? . i came up with this idea and it wasn't problematic at all in small programs . but before i apply it in a large project will it be problematic ?. thanks in advance.

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  • Android Notepadv1 Tutorial - Persistent mNoteNumber?

    - by Chris L.
    So I did the Notepadv1 tutorial. It worked great. No problems. I would however like some explanation on why the mNoteNumber remembers the last number of the item I created. So the class starts as follows: public class Notepadv1 extends ListActivity { private int mNoteNumber = 1; That's fine, I understand that. The only other time the mNoteNumber variable is used is when you add an item it creates a note with that number and then increments it to the next number as follows: private void createNote() { String noteName = "Note " + mNoteNumber++; Those are the only two references to the variable mNoteNumber. When I press the Home button and then reopen the app, I add a new note but instead of adding a second "Note 1" it remembers that the last note I added as "Note 3" so it makes "Note 4". So I don't get it. Does Java/Android remember the last state of variables? If anyone could give me some explanation that would be great THANKS!

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  • C++ privately contructed class

    - by Nona Urbiz
    How can I call a function and keep my constructor private? If I make the class static, I need to declare an object name which the compiler uses to call the constructor, which it cannot if the constructor is private (also the object would be extraneous). Here is the code I am attempting to use (it is not compilable): I want to keep the constructor private because I will later be doing a lot of checks before adding an object, modifying previous objects when all submitted variables are not unique rather than creating new objects. #include <iostream> #include <fstream> #include <regex> #include <string> #include <list> #include <map> using namespace std; using namespace tr1; class Referral { public: string url; map<string, int> keywords; static bool submit(string url, string keyword, int occurrences) { //if(Referrals.all.size == 0){ // Referral(url, keyword, occurrences); //} } private: list<string> urls; Referral(string url, string keyword, int occurrences) { url = url; keywords[keyword] = occurrences; Referrals.all.push_back(this); } }; struct All { list<Referral> all; }Referrals; int main() { Referral.submit("url", "keyword", 1); }

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  • Please tell me what is wrong with my threading!!!

    - by kiddo
    I have a function where I will compress a bunch of files into a single compressed file..it is taking a long time(to compress),so I tried implementing threading in my application..Say if I have 20 files for compression,I separated that as 5*4=20,inorder to do that I have separate variables(which are used for compression) for all 4 threads in order to avoid locks and I will wait until the 4 thread finishes..Now..the threads are working but i see no improvement in their performance..normally it will take 1 min for 20 files(for example) after implementing threading ...there is only 5 or 3 sec difference., sometimes the same. here i will show the code for 1 thread(so it is for other3 threads) //main thread myClassObject->thread1 = AfxBeginThread((AFX_THREADPROC)MyThreadFunction1,myClassObject); .... HANDLE threadHandles[4]; threadHandles[0] = myClassObject->thread1->m_hThread; .... WaitForSingleObject(myClassObject->thread1->m_hThread,INFINITE); UINT MyThreadFunction(LPARAM lparam) { CMerger* myClassObject = (CMerger*)lparam; CString outputPath = myClassObject->compressedFilePath.GetAt(0);//contains the o/p path wchar_t* compressInputData[] = {myClassObject->thread1outPath, COMPRESS,(wchar_t*)(LPCTSTR)(outputPath)}; HINSTANCE loadmyDll; loadmydll = LoadLibrary(myClassObject->thread1outPath); fp_Decompress callCompressAction = NULL; int getCompressResult=0; myClassObject->MyCompressFunction(compressInputData,loadClient7zdll,callCompressAction,myClassObject->thread1outPath, getCompressResult,minIndex,myClassObject->firstThread,myClassObject); return 0; }

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  • TDD approach for complex function

    - by jamie
    I have a method in a class for which they are a few different outcomes (based upon event responses etc). But this is a single atomic function which is to used by other applications. I have broken down the main blocks of the functionality that comprise this function into different functions and successfully taken a Test Driven Development approach to the functionality of each of these elements. These elements however aren't exposed for other applications would use. And so my question is how can/should i easily approach a TDD style solution to verifying that the single method that should be called does function correctly without a lot of duplication in testing or lots of setup required for each test? I have considered / looked at moving the blocks of functionality into a different class and use Mocking to simulate the responses of the functions used but it doesn't feel right and the individual methods need to write to variables within the main class (it felt really heath robinson). The code roughly looks like this (i have removed a lot of parameters to make things clearer along with a fair bit of irrelevant code). public void MethodToTest(string parameter) { IResponse x = null; if (function1(parameter)) { if (!function2(parameter,out x)) { function3(parameter, out x); } } // ... // more bits of code here // ... if (x != null) { x.Success(); } }

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  • Why is this giving me an infinite loop?

    - by Chase Yuan
    I was going through a code used to calculate investments until it has doubled and I received an infinite loop that I can't seem to solve. Can anyone figure out why this is giving me an infinite loop? I've gone through myself but I can't seem to find the problem. The "period" referred is how many times per year the interest is compounded. double account = 0; //declares the variables to be used double base = 0; double interest = 0; double rate = 0; double result = 0; double times = 0; int years = 0; int j; System.out.println("This is a program that calculates interest."); Scanner kbReader = new Scanner(System.in); //enters in all data System.out.print("Enter account balance: "); account = kbReader.nextDouble(); System.out.print("Enter interest rate (as decimal): "); rate = kbReader.nextDouble(); System.out.println(" " + "Years to double" + " " + "Ending balance"); base = account; result = account; for (j=0; j<3; j++){ System.out.print("Enter period: "); times = kbReader.nextDouble(); while (account < base*2){ interest = account * rate / times; account = interest + base; years++; } account = (((int)(account * 100))/100.0); //results System.out.print(" " + i + " " + account + "\n"); account = result; } The code should ask for three "periods", or three different times the entered data is compounded per year (ex annually, monthly, daily etc.) Thanks a lot!

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  • Make a PHP GET request from a PHP script and exit

    - by Abs
    Hello all, Is there something simpler than the following. I am trying to make a GET request to a PHP script and then exit the current script. I think this is a job for CURL but is there something simpler as I don't want to really worry about enabling the CURL php extension? In addition, will the below start the PHP script and then just come back and not wait for it to finish? //set GET variables $url = 'http://domain.com/get-post.php'; $fields = array( 'lname'=>urlencode($last_name), 'fname'=>urlencode($first_name) ); //url-ify the data for the GET foreach($fields as $key=>$value) { $fields_string .= $key.'='.$value.'&'; } rtrim($fields_string,'&'); //open connection $ch = curl_init(); //set the url, number of POST vars, POST data curl_setopt($ch,CURLOPT_URL,$url); curl_setopt($ch,CURLOPT_GET,count($fields)); curl_setopt($ch,CURLOPT_GETFIELDS,$fields_string); //execute GET $result = curl_exec($ch); //close connection curl_close($ch); I want to run the other script which contains functions when a condition is met so a simple include won't work as the if condition wraps around the functions, right? Please note, I am on windows machine and the code I am writing will only be used on a Windows OS. Thanks all for any help and advice

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  • StackOverflow Error at java.util.AbstractColllection.<init>(Unknown Source)

    - by thebulge
    I fixed my prior problem yesterday by just separating all the classes into separate files. Nevertheless, I wrote all the code down and seeing no errors was able to compile the program. Or so I thought. Here's the error code: Exception in thread "main" java.lang.StackOverflowError at java.util.AbstractCollection.<init>(Unknown Source) at java.util.AbstractList.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source) at java.util.Vector.<init>(Unknown Source Here are the spots where my I get the errors(marked with problem?) public class GameWorld implements IObservable, IGameWorld { // create collections class public Vector<GameObject> GameObjectList = new Vector<GameObject>(); // PROBLEM private Vector<IObserver> ObserverList = new Vector<IObserver>(); // declare objects Tank pTank = new Tank(10, 10); // other objects and variables to declare public GameWorld() { // add objects to GameObjectList } // accessors/mutators } I get another error here public class Tank extends Movable implements ISteerable { private int armorStrength; private int missileCount; public Tank() {} public Tank(int armStr, int misslCt) // problem? { armorStrength = armStr; // default armorStrength missileCount = misslCt; // default missileCount } public void setDirection(int direction) { this.setDirection(direction); // get input from left turn or right turn // updateValues(); } // access/mutators here I'm stumped on what to do here.

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  • problem using fprintf

    - by shiran bar
    I'm trying to print to a text file numerous variables yet it doesn't work. I checked and verified that i write it in the correct syntax. I also checked the return value and it's positive therefore i know it did write to the file, however when i open the file it's empty. I would be happy for some help. This is the code: I initiate DynsaleDayPtr in the main: FILE* DynsaleDayPtr = CreateTextFiles("sale_day.txt"); Create function: FILE* CreateTextFiles (char* fileName) { FILE* saleFilePtr=NULL; if((saleFilePtr=fopen(fileName,"a+"))==NULL) printf("File couldn't be opened\n"); return saleFilePtr; } The call to the function TextAddSale is done from a function that is called in the main: TextAddSale(DynSaleDayPtr,dynNumOfRecords); Bool TextAddSale (FILE* DynsaleDayPtr, int* dynNumOfRecords) { char id[6]; char name [50]; char priceChar[20]; char* tmp = NULL; int price=-1; DynamicRecord * newRec=NULL; scanf("%s%s%s",id,name,priceChar); newRec = (DynamicRecord *)malloc(sizeof(DynamicRecord)); if (newRec == NULL) return False; tmp = (char*)malloc(strlen(name)+1); if (tmp == NULL) { free (newRec); return False; } strcpy(tmp,name); newRec->productName = tmp; strcpy(newRec->productId, id); newRec->productPrice=atoi (priceChar); if (fprintf(DynsaleDayPtr,"%d %s %s %d", strlen(newRec->productName), newRec->productId, newRec->productName, newRec->productPrice)>0) { *dynNumOfRecords=(*dynNumOfRecords)+1; return True; } } thanks!

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  • First Time Working With Others?

    - by cam
    I've been at my very first programming job for about 8 months now and I've learned incredible amounts so far. Unfortunately, I'm the sole developer for a small startup company for internal applications. For the first time ever though, I'll be handing off some of my projects to someone else when I leave this job. I've documented all my projects thoroughly (at least I think so), but I still feel nervous about someone else reading my code. For example, I've always done this sort of thing. for (int i = 0; i < blah.length; i++) { //Do stuff } Should I name 'i' something descriptive? It's only a temporary variable, and will only exist within that loop, and it seems that it's pretty obvious what the loop does with 'i'. This is just one example. Another one is that I name variables differently... I don't really conform to a standard of naming besides starting all private members with an underscore. Are there any resources that could show me how to make it easier for the next developer? Are there standards for this type of thing?

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  • Overhead of calling tiny functions from a tight inner loop? [C++]

    - by John
    Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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  • How do I display core data on second view controller?

    - by jon
    I am working on my first core data iPhone application. I am using a navigation controller, and the root view controller displays 4 rows. Clicking the first row takes me to a second table view controller. However, when I click the back button, repeat the row tap, click the back button again, and tap the row a third time, I get an error. I have been researching this for a week with no success. I can reproduce the error easily: Create a new Navigation-based Application, use Core Data for storage, call it MyTest which creates MyTestAppDelegate and RootViewController. Add new UIViewController subclass, with UITableViewController and xib, call it ListViewController. Copy code from RootViewController.h and .m to ListViewController.h and .m., changing the file names appropriately. To simplify the code, I removed the trailing “_” from all variables. In RootViewController, I added #import ListViewController.h, set up an array to display 4 rows and navigate to ListViewController when clicking the first row. In ListViewController.m, I added #import MyTestAppDelegate.h” and the following code: - (void)viewDidLoad { [super viewDidLoad]; if (managedObjectContext == nil) { managedObjectContext = [(MyTestAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext]; } .. } The sequence that causes the error is tap row, return, tap row, return, tap row - error. managedObjectContext is synthesized for the third time. I appreciate your patience and your help, as this makes no sense to me. ADDENDUM: I may have a partial solution. http://www.iphonedevsdk.com/forum/iphone-sdk-development/41688-accessing-app-delegates-managed-object-context.html If I do not release the managedObjectContext in the .m file, the error goes away. Is that ok or will that cause me issues? - (void)dealloc { [fetchedResultsController release]; // [managedObjectContext release]; [super dealloc]; } ADDENDUM 2: See solution below. Sorry for the formatting issues - this was my first post.

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  • Best way to create a collection of a class

    - by smartins
    I'm trying to create some classes that allow me to retrieve and manipulate a set of backups my application will create and manage. I've come up with the following code (not tested yet), but I'm not sure if it's the best way of accomplishing this or if there's any easier/better way. I'm using Delphi 2010. I have a class that holds the backup details (TBackupItem), then I need to have a class that will hold a collection of TBackupItem and finally I'll have a class that manages the reading and writing of backups and also exposes a property that accesses the collection of TBackupItem. type TBackupItem = class private FBackupProgram: string; FBackupProgramVersion: string; // There are more variables and properties but for the sake of simplicity I've listed only two public property BackupProgram: string read FBackupProgram write FBackupProgram; property BackupProgramVersion: string read FBackupProgramVersion write FBackupProgramVersion; end; TBackupsList = class(???) private // This class will hold a list of TBackupItem. What should I use to accomplish this? end; TBackupsManager = class(TObject) private FBackups: TBackupsList; public property Backups: TBackupsList read FBackups write FBackups; end; Do you guys have any comments and/or examples on the best way of accomplishing this? Thanks!

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  • Inheritance not working

    - by Pendo826
    Hey im just practicing inheritance and i encountered a problem. Im getting an error in my car class(sub-class) that the variables in Vehicle(parent) are not visible. i didnt do anything to change this and i dont even know how to make it invisible. Can anyone help me with this. public class Vehicle { private String make, model, colour; private int registrationNumber; public Vehicle() { this.make = ""; this.model = ""; this.colour = ""; this.registrationNumber = 0; } public Vehicle(String make, String model, String colour, int registrationNumber) { this.make = make; this.model = model; this.colour = colour; this.registrationNumber = registrationNumber; } public String getMake() { return make; } public void setMake(String make) { this.make = make; } public String getModel() { return model; } public void setModel(String model) { this.model = model; } public String getColour() { return colour; } public void setColour(String colour) { this.colour = colour; } public int getRegistrationNumber() { return registrationNumber; } public void setRegistrationNumber(int registrationNumber) { this.registrationNumber = registrationNumber; } public String toString() { return "Vehicle [make=" + make + ", model=" + model + ", colour=" + colour + ", registrationNumber=" + registrationNumber + "]"; } } public Car() { super(); this.doors = 0; this.shape = ""; } public Car(int doors, String shape, String make, String model, String colour, int registrationNumber) { super(); this.doors = doors; this.shape = shape; this.make = make;//Error this.model = model;//Error this.colour = colour;//Error this.registrationNumber = registrationNumber;//Error } The error message: Description Resource Path Location Type The field Vehicle.make is not visible Car.java /VehicleApp/src line 19 Java Problem The field Vehicle.model is not visible Car.java /VehicleApp/src line 20 Java Problem The field Vehicle.colour is not visible Car.java /VehicleApp/src line 21 Java Problem The field Vehicle.registrationNumber is not visible Car.java /VehicleApp/src line 22 Java Problem

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  • Which of the following Java coding fragments is better?

    - by Simon
    This isn't meant to be subjective, I am looking for reasons based on resource utilisation, compiler performance, GC performance etc. rather than elegance. Oh, and the position of brackets doesn't count, so no stylistic comments please. Take the following loop; Integer total = new Integer(0); Integer i; for (String str : string_list) { i = Integer.parse(str); total += i; } versus... Integer total = 0; for (String str : string_list) { Integer i = Integer.parse(str); total += i; } In the first one i is function scoped whereas in the second it is scoped in the loop. I have always thought (believed) that the first one would be more efficient because it just references an existing variable already allocated on the stack, whereas the second one would be pushing and popping i each iteration of the loop. There are quite a lot of other cases where I tend to scope variables more broadly than perhaps necessary so I thought I would ask here to clear up a gap in my knowledge. Also notice that assignment of the variable on initialisation either involving the new operator or not. Do any of these sorts of semi-stylistic semi-optimisations make any difference at all?

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