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  • Simple C question

    - by Meko
    HI all. I am trying to make little program that reads data from file which has name of user and some data for that user. I am new on C , and how can i calculate this data for its user?line by line reading and adding each char in array? And how can I read line? is there any function?

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  • subscript operator on pointers

    - by Lodle
    If i have a pointer to an object that has an overloaded subscript operator ( [] ) why cant i do this: MyClass *a = new MyClass(); a[1]; but have to do this instead: MyClass *a = new MyClass(); (*a)[1];

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  • error: expected `;' before '{' token - What is the cause?

    - by melee
    Here is my implementation file: using namespace std; #include <iostream> #include <iomanip> #include <string> #include <stack> //line 5 #include "proj05.canvas.h" //----------------Constructor----------------// Canvas::Canvas() //line 10 { Title = ""; Nrow = 0; Ncol = 0; image[][100]; // line 15 position.r = 0; position.c = 0; } //-------------------Paint------------------// line 20 void Canvas::Paint(int R, int C, char Color) { cout << "Paint to be implemented" << endl; } The errors I'm getting are these: proj05.canvas.cpp: In function 'std::istream& operator>>(std::istream&, Canvas&)': proj05.canvas.cpp:11: error: expected `;' before '{' token proj05.canvas.cpp:22: error: a function-definition is not allowed here before '{' token proj05.canvas.cpp:24: error: expected `}' at end of input proj05.canvas.cpp:24: error: expected `}' at end of input These seem like simple syntax errors, but I am not sure what's wrong. Could someone decode these for me? I'd really appreciate it, thanks for your time! EDIT Here is the definition of Canvas in my .h file: #ifndef CANVAS_H #define CANVAS_H #include <iostream> #include <iomanip> #include <string> #include <stack> class Canvas { public: Canvas(); void Paint(int R, int C, char Color); const int Nrow; const int Ncol; string Title; int image[][100]; stack<int> path; struct PixelCoordinates { unsigned int r; unsigned int c; } position; }; #endif

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  • Does Boost work with IntervalZero RTX 2009?

    - by cs-79
    Hi all Rtx experts, Have anyone implemented hard real-time app on IntervalZero Rtx environment using Boost libraries? I wish to use the Boost `unordered` data structures instead of solely relying on STL::Vector. Or Array/Vector is the only data structure supported by Rtx? * Off topic question: Can we use STL::String instead of char pointer for string in Rtx? Thanks.

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  • C++ Vector vs Array (Time)

    - by vsha041
    I have got here two programs with me, both are doing exactly the same task. They are just setting an boolean array / vector to the value true. The program using vector takes 27 seconds to run whereas the program involving array with 5 times greater size takes less than 1 s. I would like to know the exact reason as to why there is such a major difference ? Are vectors really that inefficient ? Program using vectors #include <iostream> #include <vector> #include <ctime> using namespace std; int main(){ const int size = 2000; time_t start, end; time(&start); vector<bool> v(size); for(int i = 0; i < size; i++){ for(int j = 0; j < size; j++){ v[i] = true; } } time(&end); cout<<difftime(end, start)<<" seconds."<<endl; } Runtime - 27 seconds Program using Array #include <iostream> #include <ctime> using namespace std; int main(){ const int size = 10000; // 5 times more size time_t start, end; time(&start); bool v[size]; for(int i = 0; i < size; i++){ for(int j = 0; j < size; j++){ v[i] = true; } } time(&end); cout<<difftime(end, start)<<" seconds."<<endl; } Runtime - < 1 seconds Platform - Visual Studio 2008 OS - Windows Vista 32 bit SP 1 Processor Intel(R) Pentium(R) Dual CPU T2370 @ 1.73GHz Memory (RAM) 1.00 GB Thanks Amare

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  • How can I get the same strstream functionality now that's deprecated?

    - by chila
    I use to write code like this: void fun(char *buff, unsigned size) { std::strstream str(buff, size); str << "hello world: " << 5; } so I can use stream output over an arbitrary buffer. I've found this technique both efficient (no allocations) and useful (streams!). Now that std::strstream is deprecated, how can I get the same speed+flexibility that I can get with this code?

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  • variable argument list in windows va_list

    - by shrikant
    hi, I wanted to have function which will accept as foo(...) { } usage of this would be foo(1,2,3); foo(1) foo(1,2,3,4,5,5,6); va_list can be used but again for that I have to pass foo(int count, ...), as this at run time i dont know how many argument i have. any pointer would be appreciated Thanks

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  • C++ stl collections or linked lists

    - by Lucas
    I'm developing a OpenGL based simulation in C++. I'm optmizing my code now and i see throughout the code the frequently use of std:list and std:vector. What is the more performatic: to continue using C++ stl data structs or a pointer based linked list? The main operation that involve std::list and std::vector is open a iterator and loop through all items in the data structs and apply some processing

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  • How do I get the cursor back in VS2010rc winforms designer after drawing controlls?

    - by Allen
    Not sure if this is a bug or if i'm just missing something but I cannot for the life of me figure out how to get my cursor back in the winforms designer in visual studio 2010. I opened up an existing project and added a group box, now my cursor is stuck drawing group boxes. I just want the simple pointer cursor back but nothing I do seems to bring it back. I almost expected it to be on the toolbox under "Cursor" but its not.

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  • Retrieve Value from NSString

    - by Taimur Hamza
    Hi, i have a NSString instance ,i want to retrieve value from it and store it into an integer. This is wat i am doing but its not working. NSString *totalcnt; char *str = totalcnt; int a = atoi(str); Help me out. Thanks Taimur

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  • Send a variable on the heap to another thread

    - by user1201889
    I have a strange problem in C++. An address of a Boolean gets "destroyed" but it doesn't get touched. I know that there are beater way's to accomplish what I try to do, but I want to know what I do wrong. I have a main class; this main class contains a vector of another class. There is a strange problem when a new instance gets created of this object. This is how my code works: There will start a thread when the constructor gets called of the “2nd”object. This thread gets as Parameter a struct. This is the struct: struct KeyPressData { vector<bool> *AutoPressStatus; vector<int> *AutoPressTime; bool * Destroy; bool * Ready; }; The struct gets filled in the constructor: MultiBoxClient::MultiBoxClient() { //init data DestroyThread = new bool; ReadyThread = new bool; AutoThreadData = new KeyPressData; //Reseting data *DestroyThread = false; *ReadyThread = false; //KeyPressData configurating AutoThreadData->AutoPressStatus = &AutoPressStatus; AutoThreadData->AutoPressTime = &AutoPressTime; AutoThreadData->Destroy = DestroyThread; AutoThreadData->Ready = ReadyThread; //Start the keypress thread CreateThread(NULL,NULL,(LPTHREAD_START_ROUTINE)AutoKeyThread,AutoThreadData,NULL,NULL); } As long as the constructor is running will the program run fine. But when the constructor closes the address of the “AutoThreadData-Destroy” will get corrupted. The program will crash when I call the value of the pointer. void WINAPI AutoKeyThread(void * ThreadData) { KeyPressData * AutoThreadData = (KeyPressData*)ThreadData; while(true) { if(*AutoThreadData->Destroy == true) //CRASH { *AutoThreadData->Ready = true; return; } Sleep(100); } } What did I test: I logged the address of the AutoThreadData and the AutoThreadData-Destroy when the constrcutor is running and clossed; the AutoThreadData address is equal to AutoThreadData when the constructor is closed. So there is no problem here. The address of AutoThreadData-Destroy gets destroyed when the constructor is closed. But how can this happen? The Boolean is on the heap and the KeyPressData struct (AutoThreadData) is on the heap. Destroy before: 00A85328 Destroy after: FEEEFEEE Can someone maby explain why this crash? I know that I can send a pointer to my class to the thread. But I want to know what goes wrong here. That way I can learn from my mistakes. Could someone help me with this problem? Thanks!

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  • How to use length indicator in a C++ program

    - by cj
    I want to make a program in C++ that reads a file where each field will have a number before it that indicates how long it is. The problem is I read every record in object of a class; how do I make the attributes of the class dynamic? For example if the field is "john" it will read it in a 4 char array. I don't want to make an array of 1000 elements as minimum memory usage is very important.

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  • When I overload the assignment operator for my simple class array, I get the wrong answer I espect

    - by user299648
    //output is "01234 00000" but the output should be or what I want it to be is // "01234 01234" because of the assignment overloaded operator #include <iostream> using namespace std; class IntArray { public: IntArray() : size(10), used(0) { a= new int[10]; } IntArray(int s) : size(s), used(0) { a= new int[s]; } int& operator[]( int index ); IntArray& operator =( const IntArray& rightside ); ~IntArray() { delete [] a; } private: int *a; int size; int used;//for array position }; int main() { IntArray copy; if( 2>1) { IntArray arr(5); for( int k=0; k<5; k++) arr[k]=k; copy = arr; for( int j=0; j<5; j++) cout<<arr[j]; } cout<<" "; for( int j=0; j<5; j++) cout<<copy[j]; return 0; } int& IntArray::operator[]( int index ) { if( index >= size ) cout<<"ilegal index in IntArray"<<endl; return a[index]; } IntArray& IntArray::operator =( const IntArray& rightside ) { if( size != rightside.size )//also checks if on both side same object { delete [] a; a= new int[rightside.size]; } size=rightside.size; used=rightside.used; for( int i = 0; i < used; i++ ) a[i]=rightside.a[i]; return *this; }

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  • Question about C++ inner class

    - by michael
    HI, In C++ inner class, class A { public: void f1(); private: void f2(); class B { private void f3(); }; } Does an inner class (B) has a pointer to its parent class (A)? (like it does in Java). And can B calls its parent class public/private method (like it does in Java). Thank you.

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  • Get the string "System.Collections.ObjectModel.ObservableCollection" from a Type (System.type) containing a generic ObservableCollection?

    - by Guillaume Cogranne
    I got a Type whose FullName is (if this helps) : "System.Collections.ObjectModel.ObservableCollection`1[[System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]]" From that Type, I'd like to get "System.Collections.ObjectModel.ObservableCollection" as a string but I'd like to do it "cleanly", which means, without spliting the string with the char '`'. I think the strategy is to get something like a Type or something else whose FullName will be "System.Collections.ObjectModel.ObservableCollection" but I really don't manage to do it :/

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  • Function pointers in javascript using django

    - by Hulk
    Is this a valid function pointer code below, In views , def change(request): dict={} function_ptr="create()" dict.update({'function_ptr' : function_ptr}) return render_to_response('mpjt/create.html',context_instance=RequestContext(request,{'dict': dict})) In create.html $(document).ready(function() { var a = '{{dict.function_ptr}}' func_ptr(a); function create() { alert('got respponse'); } }); Thanks..

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  • Java: Are these 2 codes the same?

    - by Kevin Duke
    for (Player p : players) { p.addCard(deck.dealCard()); p.addCard(deck.dealCard()); } and for (int i = 0; i < players.size() ; i++) { Player p = players.get(i); p.addCard(deck.dealCard()); p.addCard(deck.dealCard()); } The second code yeilds a null pointer exception, what can be done to make the bottom one equivalent ?

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  • access Elf section header table

    - by idealistikz
    Assume I have the following: Elf_FIle_Header *fileHeader //struct pointer, points to start of the Elf file header fileHeader->offset //byte offset from start of file to section headers Elf_Section_Header *sectionHeader = (Elf_Section_Header *)(char *)fileHeader + fileHeader->offset Why doesn't the above line point me to the start of the section header table? How do I point to the start of the section header table?

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  • Is it any loose coupling mechanism in Objective-C + Cocoa like C# delegates or C++Qt signals+slots?

    - by Eye of Hell
    Hello. For a large programs, the standard way to chalenge a complexity is to divide a program code into small objects. Most of the actual programming languages offer this functionality via classes, so is Objective-C. But after source code is separated into small object, the second challenge is to somehow connect them with each over. Standard approaches, supported by most languages are compositon (one object is a member field of another), inheritance, templates (generics) and callbacks. More cryptic techniques include method-level delagates (C#) and signals+slots (C++Qt). I like the delegates / signals idea, since while connecting two objects i can connect individual methods with each over, without objects knowing anything of each over. For C#, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); object1.SomethingHappened += object2.HandleSomething; In this code, is object1 calls it's SomethingHappened delegate (like a normal method call) the HandleSomething method of object2 will be called. For C++Qt, it will look like this: var object1 = new CObject1(); var object2 = new CObject2(); connect( object1, SIGNAL(SomethingHappened()), object2, SLOT(HandleSomething()) ); The result will be exactly the same. This technique has some advantages and disadvantages, but generally i like it more than interfaces since if program code base grows i can change connections and add new ones without creating tons of interfaces. After examination of Objective-C i havn't found any way to use this technique i like :(. It seems that Objective-C supports message passing perfectly well, but it requres for object1 to have a pointer to object2 in order to pass it a message. If some object needs to be connected to lots of other objects, in Objective-C i will be forced to give him pointers to each of the objects it must be connected. So, the question :). Is it any approach in Objective-C programming that will closely resemble delegate / signal+slot types of connection, not a 'give first object an entire pointer to second object so it can pass a message to it'. Method-level connections are a bit more preferable to me than object-level connection ^_^.

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  • I am getting the below mentioned error in my program. what will be the solution?

    - by suvirai
    // Finaldesktop.cpp : Defines the entry point for the console application. // include include include include include using namespace std; int SearchDirectory(vector &refvecFiles, const string &refcstrRootDirectory, const string &refcstrExtension, bool bSearchSubdirectories = true) { string strFilePath; // Filepath string strPattern; // Pattern string strExtension; // Extension HANDLE hFile; // Handle to file WIN32_FIND_DATA FileInformation; // File information strPattern = refcstrRootDirectory + "\."; hFile = FindFirstFile(strPattern.c_str(), &FileInformation); if(hFile != INVALID_HANDLE_VALUE) { do { if(FileInformation.cFileName[0] != '.') { strFilePath.erase(); strFilePath = refcstrRootDirectory + "\" + FileInformation.cFileName; if(FileInformation.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) { if(bSearchSubdirectories) { // Search subdirectory int iRC = SearchDirectory(refvecFiles, strFilePath, refcstrExtension, bSearchSubdirectories); if(iRC) return iRC; } } else { // Check extension strExtension = FileInformation.cFileName; strExtension = strExtension.substr(strExtension.rfind(".") + 1); if(strExtension == refcstrExtension) { // Save filename refvecFiles.push_back(strFilePath); } } } } while(FindNextFile(hFile, &FileInformation) == TRUE); // Close handle FindClose(hFile); DWORD dwError = GetLastError(); if(dwError != ERROR_NO_MORE_FILES) return dwError; } return 0; } int main() { int iRC = 0; vector vecAviFiles; vector vecTxtFiles; // Search 'c:' for '.avi' files including subdirectories iRC = SearchDirectory(vecAviFiles, "c:", "avi"); if(iRC) { cout << "Error " << iRC << endl; return -1; } // Print results for(vector::iterator iterAvi = vecAviFiles.begin(); iterAvi != vecAviFiles.end(); ++iterAvi) cout << *iterAvi << endl; // Search 'c:\textfiles' for '.txt' files excluding subdirectories iRC = SearchDirectory(vecTxtFiles, "c:\textfiles", "txt", false); if(iRC) { cout << "Error " << iRC << endl; return -1; } // Print results for(vector::iterator iterTxt = vecTxtFiles.begin(); iterTxt != vecTxtFiles.end(); ++iterTxt) cout << *iterTxt << endl; // Wait for keystroke _getch(); return 0; }

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