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  • aio_read from file error on OS X

    - by Pyetras
    The following code: #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <aio.h> #include <errno.h> int main (int argc, char const *argv[]) { char name[] = "abc"; int fdes; if ((fdes = open(name, O_RDWR | O_CREAT, 0600 )) < 0) printf("%d, create file", errno); int buffer[] = {0, 1, 2, 3, 4, 5}; if (write(fdes, &buffer, sizeof(buffer)) == 0){ printf("writerr\n"); } struct aiocb aio; int n = 2; while (n--){ aio.aio_reqprio = 0; aio.aio_fildes = fdes; aio.aio_offset = sizeof(int); aio.aio_sigevent.sigev_notify = SIGEV_NONE; int buffer2; aio.aio_buf = &buffer2; aio.aio_nbytes = sizeof(buffer2); if (aio_read(&aio) != 0){ printf("%d, readerr\n", errno); }else{ const struct aiocb *aio_l[] = {&aio}; if (aio_suspend(aio_l, 1, 0) != 0){ printf("%d, suspenderr\n", errno); }else{ printf("%d\n", *(int *)aio.aio_buf); } } } return 0; } Works fine on Linux (Ubuntu 9.10, compiled with -lrt), printing 1 1 But fails on OS X (10.6.6 and 10.6.5, I've tested it on two machines): 1 35, readerr Is this possible that this is due to some library error on OS X, or am I doing something wrong?

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  • How is conversion of float/double to int handled in printf?

    - by Sandip
    Consider this program int main() { float f = 11.22; double d = 44.55; int i,j; i = f; //cast float to int j = d; //cast double to int printf("i = %d, j = %d, f = %d, d = %d", i,j,f,d); //This prints the following: // i = 11, j = 44, f = -536870912, d = 1076261027 return 0; } Can someone explain why the casting from double/float to int works correctly in the first case, and does not work when done in printf? This program was compiled on gcc-4.1.2 on 32-bit linux machine. EDIT: Zach's answer seems logical, i.e. use of format specifiers to figure out what to pop off the stack. However then consider this follow up question: int main() { char c = 'd'; // sizeof c is 1, however sizeof character literal // 'd' is equal to sizeof(int) in ANSI C printf("lit = %c, lit = %d , c = %c, c = %d", 'd', 'd', c, c); //this prints: lit = d, lit = 100 , c = d, c = 100 //how does printf here pop off the right number of bytes even when //the size represented by format specifiers doesn't actually match //the size of the passed arguments(char(1 byte) & char_literal(4 bytes)) return 0; } How does this work?

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  • Simple dynamic memory allocation bug.

    - by M4design
    I'm sure you (pros) can identify the bug's' in my code, I also would appreciate any other comments on my code. BTW, the code crashes after I run it. #include <stdlib.h> #include <stdio.h> #include <stdbool.h> typedef struct { int x; int y; } Location; typedef struct { bool walkable; unsigned char walked; // number of times walked upon } Cell; typedef struct { char name[40]; // Name of maze Cell **grid; // 2D array of cells int rows; // Number of rows int cols; // Number of columns Location entrance; } Maze; Maze *maz_new() { int i = 0; Maze *mazPtr = (Maze *)malloc(sizeof (Maze)); if(!mazPtr) { puts("The memory couldn't be initilised, Press ENTER to exit"); getchar(); exit(-1); } else { // allocating memory for the grid mazPtr->grid = (Cell **) malloc((sizeof (Cell)) * (mazPtr->rows)); for(i = 0; i < mazPtr->rows; i++) mazPtr->grid[i] = (Cell *) malloc((sizeof (Cell)) * (mazPtr->cols)); } return mazPtr; } void maz_delete(Maze *maz) { int i = 0; if (maz != NULL) { for(i = 0; i < maz->rows; i++) free(maz->grid[i]); free(maz->grid); } } int main() { Maze *ptr = maz_new(); maz_delete(ptr); getchar(); return 0; } Thanks in advance.

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  • Writing/Reading struct w/ dynamic array through pipe in C

    - by anrui
    I have a struct with a dynamic array inside of it: struct mystruct{ int count; int *arr; }mystruct_t; and I want to pass this struct down a pipe in C and around a ring of processes. When I alter the value of count in each process, it is changed correctly. My problem is with the dynamic array. I am allocating the array as such: mystruct_t x; x.arr = malloc( howManyItemsDoINeedToStore * sizeof( int ) ); Each process should read from the pipe, do something to that array, and then write it to another pipe. The ring is set up correctly; there's no problem there. My problem is that all of the processes, except the first one, are not getting a correct copy of the array. I initialize all of the values to, say, 10 in the first process; however, they all show up as 0 in the subsequent ones. for( j = 0; j < howManyItemsDoINeedToStore; j++ ){ x.arr[j] = 10; } Initally: 10 10 10 10 10 After Proc 1: 9 10 10 10 15 After Proc 2: 0 0 0 0 0 After Proc 3: 0 0 0 0 0 After Proc 4: 0 0 0 0 0 After Proc 5: 0 0 0 0 0 After Proc 1: 9 10 10 10 15 After Proc 2: 0 0 0 0 0 After Proc 3: 0 0 0 0 0 After Proc 4: 0 0 0 0 0 After Proc 5: 0 0 0 0 0 Now, if I alter my code to, say, struct mystruct{ int count; int arr[10]; }mystruct_t; everything is passed correctly down the pipe, no problem. I am using READ and WRITE, in C: write( STDOUT_FILENO, &x, sizeof( mystruct_t ) ); read( STDIN_FILENO, &x, sizeof( mystruct_t ) ); Any help would be appreciated. Thanks in advance!

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  • create an independent hidden process

    - by Jessica
    I'm creating an application with its main window hidden by using the following code: STARTUPINFO siStartupInfo; PROCESS_INFORMATION piProcessInfo; memset(&siStartupInfo, 0, sizeof(siStartupInfo)); memset(&piProcessInfo, 0, sizeof(piProcessInfo)); siStartupInfo.cb = sizeof(siStartupInfo); siStartupInfo.dwFlags = STARTF_USESHOWWINDOW | STARTF_FORCEOFFFEEDBACK | STARTF_USESTDHANDLES; siStartupInfo.wShowWindow = SW_HIDE; if(CreateProcess(MyApplication, "", 0, 0, FALSE, 0, 0, 0, &siStartupInfo, &piProcessInfo) == FALSE) { // blah return 0; } Everything works correctly except my main application (the one calling this code) window loses focus when I open the new program. I tried lowering the priority of the new process but the focus problem is still there. Is there anyway to avoid this? furthermore, is there any way to create another process without using CreateProcess (or any of the API's that call CreateProcess like ShellExecute)? My guess is that my app is losing focus because it was given to the new process, even when it's hidden. To those of you curious out there that will certainly ask the usual "why do you want to do this", my answer is because I have a watchdog process that cannot be a service and it gets started whenever I open my main application. Satisfied? Thanks for the help. Code will be appreciated. Jess.

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  • Getting base address of a process

    - by yoni0505
    I'm trying to make a program that read the timer value from Minesweeper. (OS is windows 7 64bit) Using cheat engine I found the base address of the variable, but it changes every time I run Minesweeper. What do I need to do to find out the base address automatically? Does it have something to do with the executable base address? Here's my code: #include <windows.h> #include <iostream> using namespace std; int main() { DWORD baseAddress = 0xFF1DAA38;//always changing DWORD offset1 = 0x18; DWORD offset2 = 0x20; DWORD pAddress1; DWORD pAddress2; float value = 0; DWORD pid; HWND hwnd; hwnd = FindWindow(NULL,"Minesweeper"); if(!hwnd)//didn't find the window { cout <<"Window not found!\n"; cin.get(); } else { GetWindowThreadProcessId(hwnd,&pid); HANDLE phandle = OpenProcess(PROCESS_VM_READ,0,pid);//get permission to read if(!phandle)//failed to get permission { cout <<"Could not get handle!\n"; cin.get(); } else { ReadProcessMemory(phandle,(void*)(baseAddress),&pAddress1,sizeof(pAddress1),0); ReadProcessMemory(phandle,(void*)(pAddress1 + offset1),&pAddress2,sizeof(pAddress2),0); while(1) { ReadProcessMemory(phandle,(void*)(pAddress2 + offset2),&value,sizeof(value),0); cout << value << "\n"; Sleep(1000); } } } }

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  • CGI Buffering issue

    - by Punit
    I have a server side C based CGI code as: cgiFormFileSize("UPDATEFILE", &size); //UPDATEFILE = file being uploaded cgiFormFileName("UPDATEFILE", file_name, 1024); cgiFormFileContentType("UPDATEFILE", mime_type, 1024); buffer = malloc(sizeof(char) * size); if (cgiFormFileOpen("UPDATEFILE", &file) != cgiFormSuccess) { exit(1); } output = fopen("/tmp/cgi.tar.gz", "w+"); printf("The size of file is: %d bytes", size); inc = size/(1024*100); while (cgiFormFileRead(file, b, sizeof(b), &got_count) == cgiFormSuccess) { fwrite(b,sizeof(char),got_count,output); i++; if(i == inc && j<=100) { ***inc_pb*** = j; i = 0; j++; // j is the progress bar increment value } } cgiFormFileClose(file); retval = system("mkdir /tmp/update-tmp;\ cd /tmp/update-tmp;\ tar -xzf ../cgi.tar.gz;\ bash -c /tmp/update-tmp/update.sh"); However, this doesn't work the way as is seen above. Instead of printing 1,2,...100 to progress_bar.txt one by one it prints at ONE GO, seems it buffers and then writes to the file. fflush() also didn't work. Any clue/suggestion would be really appreciated.

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  • How memset initializes an array of integers by -1?

    - by haccks
    The manpage says about memset: #include <string.h> void *memset(void *s, int c, size_t n) The memset() function fills the first n bytes of the memory area pointed to by s with the constant byte c. It is clear that memset can't be used to initialize int array as shown below: int a[10]; memset(a, 1, sizeof(a)); it is because int is represented by 4 bytes (say) and one can not get the desired value for the integers in array a. But I often see the programmers use memset to set the int array elements to either 0 or -1. int a[10]; int b[10]; memset(a, 0, sizeof(a)); memset(b, -1, sizeof(b)); As per my understanding, initializing with integer 0 is OK because 0 can be represented in 1 byte (may be I am wrong in this context). But how it is possible to initialize b with -1 (a 4 bytes value)?

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  • iPhone SpeakHere example produces different number of samples

    - by pion
    I am looking at the SpeakHere example and added the following: // Overriding the output audio route UInt32 audioRouteOverride = kAudioSessionOverrideAudioRoute_Speaker; AudioSessionSetProperty(kAudioSessionProperty_OverrideAudioRoute, sizeof (audioRouteOverride), &audioRouteOverride); assert(status == noErr); // Changing the default output route. The new output route remains in effect unless you change the audio session category. This option is available starting in iPhone OS 3.1. UInt32 doChangeDefaultRoute = 1; status = AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryDefaultToSpeaker, sizeof(doChangeDefaultRoute), &doChangeDefaultRoute); assert(status == noErr); // Enable Bluetooth. See audioRouteOverride & doChangeDefaultRoute above // http://developer.apple.com/iphone/library/documentation/Audio/Conceptual/AudioSessionProgrammingGuide/Cookbook/Cookbook.html#//apple_ref/doc/uid/TP40007875-CH6-SW2 UInt32 allowBluetoothInput = 1; status = AudioSessionSetProperty(kAudioSessionProperty_OverrideCategoryEnableBluetoothInput, sizeof(allowBluetoothInput), &allowBluetoothInput); assert(status == noErr); Also, void AQRecorder::handleInputBufferCallback(void *aqData, ... ... if (inNumPackets > 0) { NSLog(@"Number of samples = %d", inBuffer->mAudioDataByteSize/2); // print out the number of sample status = AudioFileWritePackets(aqr->mAudioFile, FALSE, inBuffer->mAudioDataByteSize, inPacketDesc, aqr->mCurrentPacket, &inNumPackets, inBuffer->mAudioData); assert(status == noErr); aqr->mCurrentPacket += inNumPackets; } ... Notice the "NSLog(@"Number of samples = %d", inBuffer-mAudioDataByteSize/2); // print out the number of sample" statement above. I am using iPhone SDK 3.1.3. I got the following results The number of samples is around 44,100 on Simulator The number of samples is around 22,000 on iPhone The number of samples is around 4,000 on iPhone using Jawbone Bluetooth I am new on this. Why did itproduce different number of samples? Thanks in advance for your help.

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  • std::conditional compile-time branch evaluation

    - by cmannett85
    Compiling this: template < class T, class Y, class ...Args > struct isSame { static constexpr bool value = std::conditional< sizeof...( Args ), typename std::conditional< std::is_same< T, Y >::value, isSame< Y, Args... >, // Error! std::false_type >::type, std::is_same< T, Y > >::type::value; }; int main() { qDebug() << isSame< double, int >::value; return EXIT_SUCCESS; } Gives me this compiler error: error: wrong number of template arguments (1, should be 2 or more) The issue is that isSame< double, int > has an empty Args parameter pack, so isSame< Y, Args... > effectively becomes isSame< Y > which does not match the signature. But my question is: Why is that branch being evaluated at all? sizeof...( Args ) is false, so the inner std:conditional should not be evaluated. This isn't a runtime piece of code, the compiler knows that sizeof..( Args ) will never be true with the given template types. If you're curious, it's supposed to be a variadic version of std::is_same, not that it works...

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  • Inorder tree traversal in binary tree in C

    - by srk
    In the below code, I'am creating a binary tree using insert function and trying to display the inserted elements using inorder function which follows the logic of In-order traversal.When I run it, numbers are getting inserted but when I try the inorder function( input 3), the program continues for next input without displaying anything. I guess there might be a logical error.Please help me clear it. Thanks in advance... #include<stdio.h> #include<stdlib.h> int i; typedef struct ll { int data; struct ll *left; struct ll *right; } node; node *root1=NULL; // the root node void insert(node *root,int n) { if(root==NULL) //for the first(root) node { root=(node *)malloc(sizeof(node)); root->data=n; root->right=NULL; root->left=NULL; } else { if(n<(root->data)) { root->left=(node *)malloc(sizeof(node)); insert(root->left,n); } else if(n>(root->data)) { root->right=(node *)malloc(sizeof(node)); insert(root->right,n); } else { root->data=n; } } } void inorder(node *root) { if(root!=NULL) { inorder(root->left); printf("%d ",root->data); inorder(root->right); } } main() { int n,choice=1; while(choice!=0) { printf("Enter choice--- 1 for insert, 3 for inorder and 0 for exit\n"); scanf("%d",&choice); switch(choice) { case 1: printf("Enter number to be inserted\n"); scanf("%d",&n); insert(root1,n); break; case 3: inorder(root1); break; default: break; } } }

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  • CreateProcess() fails with an access violation

    - by John Doe
    My aim is to execute an external executable in my program. First, I used system() function, but I don't want the console to be seen to the user. So, I searched a bit, and found CreateProcess() function. However, when I try to pass a parameter to it, I don't know why, it fails. I took this code from MSDN, and changed a bit: #include <windows.h> #include <stdio.h> #include <tchar.h> void _tmain( int argc, TCHAR *argv[] ) { STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); ZeroMemory( &pi, sizeof(pi) ); /* if( argc != 2 ) { printf("Usage: %s [cmdline]\n", argv[0]); return; } */ // Start the child process. if( !CreateProcess( NULL, // No module name (use command line) L"c:\\users\\e\\desktop\\mspaint.exe", // Command line NULL, // Process handle not inheritable NULL, // Thread handle not inheritable FALSE, // Set handle inheritance to FALSE 0, // No creation flags NULL, // Use parent's environment block NULL, // Use parent's starting directory &si, // Pointer to STARTUPINFO structure &pi ) // Pointer to PROCESS_INFORMATION structure ) { printf( "CreateProcess failed (%d).\n", GetLastError() ); return; } // Wait until child process exits. WaitForSingleObject( pi.hProcess, INFINITE ); // Close process and thread handles. CloseHandle( pi.hProcess ); CloseHandle( pi.hThread ); } However, this code crated access violation somehow. Can I execute mspaint without showing user the console? Thank you very much.

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  • c programming malloc question

    - by user535256
    Hello guys, Just got query regarding c malloc() function. I am read()ing x number of bytes from a file to get lenght of filename, like ' read(file, &namelen, sizeof(unsigned char)); ' . The variable namelen is a type unsigned char and was written into file as that type (1 byte). Now namelen has the lenght of filename ie namelen=8 if file name was 'data.txt', plus extra /0 at end, that working fine. Now I have a structure recording file info, ie filename, filelenght, content size etc. struct fileinfo { char *name; ...... other variable like size etc }; struct fileinfo *files; Question: I want to make that files.name variable the size of namelen ie 8 so I can successfully write the filename into it, like ' files[i].name = malloc(namelen) ' However, I dont want it to be malloc(sizeof(namelen)) as that would make it file.name[1] as the size of its type unsigned char. I want it to be the value thats stored inside variable &namelen ie 8 so file.name[8] so data.txt can be read() from file as 8 bytes and written straight into file.name[8? Is there a way to do this my current code is this and returns 4 not 8 files[i].name = malloc(namelen); //strlen(files[i].name) - returns 4 //perhaps something like malloc(sizeof(&namelen)) but does not work Thanks for any suggestions Have tried suggested suggestions guys, but I now get a segmentation fault error using: printf("\nsizeofnamelen=%x\n",namelen); //gives 8 for data.txt files[i].name = malloc(namelen + 1); read(file, &files[i].name, namelen); int len=strlen(files[i].name); printf("\nnamelen=%d",len); printf("\nname=%s\n",files[i].name); When I try to open() file with that files[i].name variable it wont open so the data does not appear to be getting written inside the read() &files[i].name and strlen() causes segemntation error as well as trying to print the filename

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  • OpenGL 3.3 different colours with fragment shader [solved]

    - by Andrew Seymour
    I'm an OpenGL newbie. I'm trying to colour 3 circles but only 3 white circles are appearing. n is 3 in this example. Each vertice has 5 points, 2 for position and 3 for color Here is where I think a problem may lie: glEnableVertexAttribArray(0); glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer); glVertexAttribPointer( 0, 2, GL_FLOAT, GL_FALSE, 5*sizeof(float), (void*)0 ); glEnableVertexAttribArray(1); glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE, 5*sizeof(float), (void*)(2*sizeof(float)) ); glDrawElements(GL_TRIANGLES, 20 * 3 * n, GL_UNSIGNED_INT, 0); glDisableVertexAttribArray(0); glDisableVertexAttribArray(1); My shaders: #version 330 core in vec3 Color; out vec4 outColor; void main() { outColor = vec4(Color, 1.0); } #version 330 core layout(location = 0) in vec2 position; layout(location = 1) in vec3 color out vec3 Color void main(){ gl_Position = vec4(position, 0.0, 1.0); Color = color; } Thanks for taking a look Andy EDIT: layout(location = 1) in vec3 color out vec3 Color layout(location = 1) in vec3 color; out vec3 Color;

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  • Access to map data

    - by herzl shemuelian
    I have a complex map that defined typedef short short1 typedef short short2 typedef map<short1,short2> data_list; typedef map<string,list> table_list; I have a class that fill table_list class GroupingClass { table_list m_table_list; string Buildkey(OD e1){ string ostring; ostring+=string(e1.m_Date,sizeof(Date)); ostring+=string(e1.m_CT,sizeof(CT)); ostring+=string(e1.m_PT,sizeof(PT)); return ostring; } void operator() (const map<short1,short2>::value_type& myPair) { OptionsDefine e1=myPair.second; string key=Buildkey(e1); m_table_list[key][e1.m_short2]=e1.m_short2; } operator table_list() { return m_table_list; } }; and I use it by table_list TL2 GroupingClass gc; TL2=for_each(mapOD.begin(), mapOD.end(), gc); but when I try to access to internal map I have problems for example data_list tmp; tmp=TL2["AAAA"]; short i=tmp[1]; //I dont update i variable but if i use a loop by itrator this work properly why this no work at first way thanks herzl

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  • Query about running a program through valgrind and getting false results comparing to other systems.

    - by FILIaS
    Yesterday i posted this: What's the problem with this code? [hashtable in C] and paxdiablo offered to help me. He posted a sample of code and asked me to run it through valgrind on my machine. This code normally generates: 12,4 But on my machine, i get 24,8. The doubled! I'm just curious why is that happening. Hope sb has a good explaination. I post also paxdiablo's code (for anyone who cant find it.) #include <stdio.h> #include <stdlib.h> typedef struct HashTable { int size ; struct List *head; struct List *tail; } HashTable; typedef struct List { char *number; char *name; int time; struct List *next; } List; #define size_of_table 211 HashTable *createHashTable(void) { HashTable *new_table = malloc(sizeof(*new_table)*size_of_table); //line 606 printf ("%d\n", sizeof(*new_table)); printf ("%d\n", sizeof(new_table)); if (new_table == NULL) { return NULL; } int i=0; for(i; i<size_of_table; i++) { new_table[i].size=0; new_table[i].head=NULL; new_table[i].tail=NULL; } return new_table; } int main(void) { HashTable *x = createHashTable(); free (x); return 0; }

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  • Time taken for memcpy decreases after certain point

    - by tss
    I ve a code which increases the size of the memory(identified by a pointer) exponentially. Instead of realloc, I use malloc followed by memcpy.. Something like this.. int size=5,newsize; int *c = malloc(size*sizeof(int)); int *temp; while(1) { newsize=2*size; //begin time temp=malloc(newsize*sizeof(int)); memcpy(temp,c,size*sizeof(int)); //end time //print time in mili seconds c=temp; size=newsize; } Thus the number of bytes getting copied is increasing exponentially. The time required for this task also increases almost linearly with the increase in size. However after certain point, the time taken abruptly reduces to a very small value and then remains constant. I recorded time for similar code, copyin data(Of my own type) 5 -> 10 - 2 ms 10 -> 20 - 2 ms . . 2560 -> 5120 - 5 ms . . 20480 -> 40960 - 30 ms 40960 -> 91920 - 58 ms 367680 -> 735360 - 2 ms 735360 -> 1470720 - 2 ms 1470720 -> 2941440 - 2 ms What is the reason for this drop in time ? Does a more optimal memcpy method get called when the size is large ?

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  • C++ Printing: Printer jams, what am I doing wrong?

    - by Kleas
    I have a problem with printing in C++. As far as I know, this code used to work on my previous printer, but ever since I got another one (an HP C7280) it started giving problems. Whenever I try to print anything, even an empty page, the page JAMS the printer. I have to manualy remove the page from the printer. I have no clue why this is happening. Am I doing something wrong, is it a driver problem, are there better ways to print in C++? I am using Windows 7 64 bit, but this problem also presented itself when I was using Windows Vista 64 bit. I use the following code: PRINTDLG pd; ZeroMemory(&pd, sizeof(pd)); pd.lStructSize = sizeof(pd); pd.hwndOwner = mainWindow; pd.hDevMode = NULL; pd.hDevNames = NULL; pd.Flags = PD_USEDEVMODECOPIESANDCOLLATE | PD_RETURNDC; pd.nCopies = 1; pd.nMinPage = 1; pd.nMaxPage = 0xFFFF; if (PrintDlg(&pd)==TRUE) { DOCINFO di; di.cbSize = sizeof(DOCINFO); di.lpszDocName = "Rumitec en Roblaco Print"; di.lpszOutput = (LPTSTR)NULL; di.fwType = 0; // Start printing StartDoc(pd.hDC, &di); StartPage(pd.hDC); initPrinter(pd.hDC); // ... // Do some drawing // ... // End printing EndPage(pd.hDC); EndDoc(pd.hDC); DeleteDC(pd.hDC); } Am I doing something wrong? Alternatively, is there a better, easier, more modern way to do it?

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  • C++: Weird Segmentation fault.

    - by Kleas
    I am trying to print something using C++. However, I am running into a strange bug that has left me clueless, I use the following code: PRINTDLG pd; ZeroMemory(&pd, sizeof(pd)); pd.lStructSize = sizeof(pd); pd.Flags = PD_RETURNDEFAULT; PrintDlg(&pd); // Set landscape DEVMODE* pDevMode = (DEVMODE*)GlobalLock(pd.hDevMode); pDevMode->dmOrientation = DMORIENT_LANDSCAPE; pd.hwndOwner = mainWindow; pd.Flags = PD_RETURNDC | PD_NOSELECTION; GlobalUnlock(pd.hDevMode); if (PrintDlg(&pd)) { DOCINFO di; di.cbSize = sizeof(DOCINFO); di.lpszDocName = "Test Print"; di.lpszOutput = (LPTSTR)NULL; di.fwType = 0; //start printing StartDoc(pd.hDC, &di); int a; int b; int c; int d; int e; int f; // int g; // Uncomment this -> CRASH EndDoc(pd.hDC); DeleteDC(pd.hDC); } else { cout << "Did not print: " << CommDlgExtendedError() << endl; } The moment I uncomment 'int g;' I get a: "Program received signal SIGSEGV, Segmentation fault." I use codeblocks and the mingw compiler, both up to date. What could be causing this?

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  • char array split ip with strtok

    - by user1480139
    I'm trying to split a IP address like 127.0.0.1 from a file: using following C code: pch2 = strtok (ip,"."); printf("\npart 1 ip: %s",pch2); pch2 = strtok (NULL,"."); printf("\npart 2 ip: %s",pch2); And IP is a char ip[500], that containt an ip. When printing it prints 127 as part 1 but as part 2 it prints NULL? Can someone help me? EDIT: Whole function: FILE *file = fopen ("host.txt", "r"); char * pch; char * pch2; char ip[BUFFSIZE]; IPPart result; if (file != NULL) { char line [BUFFSIZE]; while(fgets(line,sizeof line,file) != NULL) { if(line[0] != '#') { //fputs(line,stdout); pch = strtok (line," "); printf ("%s\n",pch); strncpy(ip, pch, sizeof(pch)-1); ip[sizeof(pch)-1] = '\0'; //pch = strtok (line, " "); pch = strtok (NULL," "); printf("%s",pch); pch2 = strtok (ip,"."); printf("\nDeel 1 ip: %s",pch2); pch2 = strtok (NULL,"."); printf("\nDeel 2 ip: %s",pch2); //if(strcmp(pch,url) == 0) //{ // result.part1 = //} } } fclose(file); }

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  • C++ dynamic array causes segmentation fault at assigment

    - by opc0de
    I am doing a application witch uses sockets so I am holding in an array the sockets handles.I have the following code: while(0 == 0){ int * tx = (int*)(malloc((nr_con + 2) * sizeof(int))); if (conexiuni != NULL) { syslog(LOG_NOTICE,"Ajung la eliberare %d",nr_con); memcpy(&tx[0],&conexiuni[0],(sizeof(int) * (nr_con))); syslog(LOG_NOTICE,"Ajung la eliberare %d",nr_con); free(conexiuni); } conexiuni = tx; syslog(LOG_NOTICE,"Ajung la mama %d",nr_con); //The line bellow causes a segfault at second connection if ((conexiuni[nr_con] = accept(hsock,(sockaddr*)(&sadr),&addr_size)) != -1) { nr_con++; syslog(LOG_NOTICE,"Primesc de la %s",inet_ntoa(sadr.sin_addr)); syslog(LOG_NOTICE,"kkt %d",conexiuni[nr_con - 1]); int * sz = (int*)malloc(sizeof(int)); *sz = conexiuni[nr_con - 1]; syslog(LOG_NOTICE,"after %d",*sz); pthread_create(&tidi,0,&ConexiuniHandler, sz); } } When I connect the second time when I assign the array the program crashes. What am I doing wrong? I tried the same code on Windows and it works well but on Linux it crashes.

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  • C++ new memory allocation fragmentation

    - by tamulj
    I was trying to look at the behavior of the new allocator and why it doesn't place data contiguously. My code: struct ci { char c; int i; } template <typename T> void memTest() { T * pLast = new T(); for(int i = 0; i < 20; ++i) { T * pNew = new T(); cout << (pNew - pLast) << " "; pLast = pNew; } } So I ran this with char, int, ci. Most allocations were a fixed length from the last, sometimes there were odd jumps from one available block to another. sizeof(char) : 1 Average Jump: 64 bytes sizeof(int): 4 Average Jump: 16 sizeof(ci): 8 (int has to be placed on a 4 byte align) Average Jump: 9 Can anyone explain why the allocator is fragmenting memory like this? Also why is the jump for char so much larger then ints and a structure that contains both an int and char.

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  • Problem with reading and writing to binary file in C++

    - by Reem
    I need to make a file that contains "name" which is a string -array of char- and "data" which is array of bytes -array of char in C++- but the first problem I faced is how to separate the "name" from the "data"? newline character could work in this case (assuming that I don't have "\n" in the name) but I could have special characters in the "data" part so there's no way to know when it ends so I'm putting an int value in the file before the data which has the size of the "data"! I tried to do this with code as follow: if((fp = fopen("file.bin","wb")) == NULL) { return false; } char buffer[] = "first data\n"; fwrite( buffer ,1,sizeof(buffer),fp ); int number[1]; number[0]=10; fwrite( number ,1,1, fp ); char data[] = "1234567890"; fwrite( data , 1, number[0], fp ); fclose(fp); but I didn't know if the "int" part was right, so I tried many other codes including this one: char buffer[] = "first data\n"; fwrite( buffer ,1,sizeof(buffer),fp ); int size=10; fwrite( &size ,sizeof size,1, fp ); char data[] = "1234567890"; fwrite( data , 1, number[0], fp ); I see 4 "NULL" characters in the file when I open it instead of seeing an integer. Is that normal? The other problem I'm facing is reading that again from the file! The code I tried to read didn't work at all :( I tried it with "fread" but I'm not sure if I should use "fseek" with it or it just read the other character after it. Forgive me but I'm a beginner :(

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  • Using the read function to read in a file.

    - by robUK
    Hello, gcc 4.4.1 I am using the read function to read in a wave file. However, when it gets to the read function. Execution seems to stop and freezes. I am wondering if I am doing anything wrong with this. The file size test-short.wave is: 514K. What I am aiming for is to read the file into the memory buffer chunks at a time. Currently I just testing this. Many thanks for any suggestions, #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <fcntl.h> #include <string.h> #include <unistd.h> int main(void) { char buff = malloc(10240); int32_t fd = 0; int32_t bytes_read = 0; char *filename = "test-short.wav"; /* open wave file */ if((fd = (open(filename, O_RDWR)) == -1)) { fprintf(stderr, "open [ %s ]\n", strerror(errno)); return 1; } printf("Opened file [ %s ]\n", filename); printf("sizeof(buff) [ %d ]\n", sizeof(buff)); printf("strlen(buff) [ %d ]\n", strlen(buff)); bytes_read = read(fd, buff, sizeof(buff)); printf("Bytes read [ %d ]\n", bytes_read); return 0; }

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  • Creating independent process!

    - by Neha
    I am trying to create a process from a service in C++. This new process is creating as a child process. I want to create an independent process and not a child process... I am using CreateProcess function for the same. Since the new process i create is a child process when i try to kill process tree at the service level it is killing the child process too... I dont want this to happen. I want the new process created to run independent of the service. Please advice on the same.. Thanks.. Code STARTUPINFO si; PROCESS_INFORMATION pi; ZeroMemory( &si, sizeof(si) ); si.cb = sizeof(si); // Start the child process. ZeroMemory( &pi, sizeof(pi) ); si.dwFlags = STARTF_USESHOWWINDOW; if(bRunOnWinLogonDesktop) { if(csDesktopName.empty()) si.lpDesktop = _T("winsta0\\default"); else _tcscpy(si.lpDesktop, csDesktopName.c_str()); } if(bHide) si.wShowWindow = SW_HIDE; /* maybe even SW_HIDE */ else si.wShowWindow = SW_SHOW; /* maybe even SW_HIDE */ TCHAR szCmdLine[512]; _tcscpy(szCmdLine, csCmdLine.c_str()); if( !CreateProcess( NULL, szCmdLine, NULL, NULL, FALSE, CREATE_NEW_PROCESS_GROUP, NULL, NULL, &si, &pi ) )

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