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  • SUA + Visual Studio + pthreads

    - by vasek7
    Hi, I cannot compile this code under SUA: #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <pthread.h> void * thread_function(void *arg) { printf("thread_function started. Arg was %s\n", (char *)arg); // pause for 3 seconds sleep(3); // exit and return a message to another thread // that may be waiting for us to finish pthread_exit ("thread one all done"); } int main() { int res; pthread_t a_thread; void *thread_result; // create a thread that starts to run ‘thread_function’ pthread_create (&a_thread, NULL, thread_function, (void*)"thread one"); printf("Waiting for thread to finish...\n"); // now wait for new thread to finish // and get any returned message in ‘thread_result’ pthread_join(a_thread, &thread_result); printf("Thread joined, it returned %s\n", (char *)thread_result); exit(0); } I'm running on Windows 7 Ultimate x64 with Visual Studio 2008 and 2010 and I have installed: Windows Subsystem for UNIX Utilities and SDK for Subsystem for UNIX-based Applications in Microsoft Windows 7 and Windows Server 2008 R2 Include directories property of Visual Studio project is set to "C:\Windows\SUA\usr\include" What I have to configure in order to compile and run (and possibly debug) pthreads programs in Visual Studio 2010 (or 2008)?

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  • Help with C puzzle

    - by Javier Badia
    I found a site with some complicated C puzzles. Right now I'm dealing with this: The following is a piece of C code, whose intention was to print a minus sign 20 times. But you can notice that, it doesn't work. #include <stdio.h> int main() { int i; int n = 20; for( i = 0; i < n; i-- ) printf("-"); return 0; } Well fixing the above code is straight-forward. To make the problem interesting, you have to fix the above code, by changing exactly one character. There are three known solutions. See if you can get all those three. I cannot figure out how to solve. I know that it can be fixed by changing -- to ++, but I can't figure out what single character to change to make it work.

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  • Calling unmanaged dll from C#. Take 2

    - by Charles Gargent
    I have written a c# program that calls a c++ dll that echoes the commandline args to a file When the c++ is called using the rundll32 command it displays the commandline args no problem, however when it is called from within the c# it doesnt. I asked this question to try and solve my problem, but I have modified it my test environment and I think it is worth asking a new question. Here is the c++ dll #include "stdafx.h" #include "stdlib.h" #include <stdio.h> #include <iostream> #include <fstream> using namespace std; BOOL APIENTRY DllMain( HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved ) { return TRUE; } extern "C" __declspec(dllexport) int WINAPI CMAKEX( HWND hwnd, HINSTANCE hinst, LPCSTR lpszCommandLine, DWORD dwReserved) { ofstream SaveFile("output.txt"); SaveFile << lpszCommandLine; SaveFile.close(); return 0; } Here is the c# app using System; using System.Collections.Generic; using System.Text; using System.Security.Cryptography; using System.Runtime.InteropServices; using System.Net; namespace nac { class Program { [DllImport("cmakca.dll", SetLastError = true, CharSet = CharSet.Unicode)] static extern bool CMAKEX(IntPtr hwnd, IntPtr hinst, string lpszCmdLine, int nCmdShow); static void Main(string[] args) { string cmdLine = @"/source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp"""; const int SW_SHOWNORMAL = 1; CMAKEX(IntPtr.Zero, IntPtr.Zero, cmdLine, SW_SHOWNORMAL).ToString(); } } } The output from the rundll32 command is rundll32 cmakex.dll,CMAKEX /source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp" /source_filename proxy-1.txt /backup_filename proxy.bak /DialRasEntry NULL /TunnelRasEntry DSLVPN /profile ""C:\Documents and Settings\Administrator\Application Data\Microsoft\Network\Connections\Cm\dslvpn.cmp" however the output when the c# app runs is /

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  • C-macro: set a register field defined by a bit-mask to a given value

    - by geschema
    I've got 32-bit registers with field defined as bit-masks, e.g. #define BM_TEST_FIELD 0x000F0000 I need a macro that allows me to set a field (defined by its bit-mask) of a register (defined by its address) to a given value. Here's what I came up with: #include <stdio.h> #include <assert.h> typedef unsigned int u32; /* * Set a given field defined by a bit-mask MASK of a 32-bit register at address * ADDR to a value VALUE. */ #define SET_REGISTER_FIELD(ADDR, MASK, VALUE) \ { \ u32 mask=(MASK); u32 value=(VALUE); \ u32 mem_reg = *(volatile u32*)(ADDR); /* Get current register value */ \ assert((MASK) != 0); /* Null masks are not supported */ \ while(0 == (mask & 0x01)) /* Shift the value to the left until */ \ { /* it aligns with the bit field */ \ mask = mask >> 1; value = value << 1; \ } \ mem_reg &= ~(MASK); /* Clear previous register field value */ \ mem_reg |= value; /* Update register field with new value */ \ *(volatile u32*)(ADDR) = mem_reg; /* Update actual register */ \ } /* Test case */ #define BM_TEST_FIELD 0x000F0000 int main() { u32 reg = 0x12345678; printf("Register before: 0x%.8X\n", reg);/* should be 0x12345678 */ SET_REGISTER_FIELD(&reg, BM_TEST_FIELD, 0xA); printf("Register after: 0x%.8X\n", reg); /* should be 0x123A5678 */ return 0; } Is there a simpler way to do it?

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  • valgrind complains doing a very simple strtok in c

    - by monkeyking
    Hi I'm trying to tokenize a string by loading an entire file into a char[] using fread. For some strange reason it is not always working, and valgrind complains in this very small sample program. Given an input like test.txt first second And the following program #include <stdio.h> #include <string.h> #include <stdlib.h> #include <sys/stat.h> //returns the filesize in bytes size_t fsize(const char* fname){ struct stat st ; stat(fname,&st); return st.st_size; } int main(int argc, char *argv[]){ FILE *fp = NULL; if(NULL==(fp=fopen(argv[1],"r"))){ fprintf(stderr,"\t-> Error reading file:%s\n",argv[1]); return 0; } char buffer[fsize(argv[1])]; fread(buffer,sizeof(char),fsize(argv[1]),fp); char *str = strtok(buffer," \t\n"); while(NULL!=str){ fprintf(stderr,"token is:%s with strlen:%lu\n",str,strlen(str)); str = strtok(NULL," \t\n"); } return 0; } compiling like gcc test.c -std=c99 -ggdb running like ./a.out test.txt thanks

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  • problem when trying to empty a stack in c

    - by frx08
    Hi all, (probably it's a stupid thing but) I have a problem with a stack implementation in C language, when I try to empty it, the function to empty the stack does an infinite loop.. the top of the stack is never null. where I commit an error? thanks bye! #include <stdio.h> #include <stdlib.h> typedef struct stack{ size_t a; struct stack *next; } stackPos; typedef stackPos *ptr; void push(ptr *top, size_t a){ ptr temp; temp = malloc(sizeof(stackPos)); temp->a = a; temp->next = *top; *top = temp; } void freeStack(ptr *top){ ptr temp = *top; while(*top!=NULL){ //the program does an infinite loop *top = temp->next; free(temp); } } int main(){ ptr top = NULL; push(&top, 4); push(&top, 8); //down here the problem freeStack(&top); return 0; }

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  • VERY simple C program won't compile with VC 64

    - by Paperflyer
    Here is a very simple C program: #include <stdio.h> int main (int argc, char *argv[]) { printf("sizeof(short) = %d\n",(int)sizeof(short)); printf("sizeof(int) = %d\n",(int)sizeof(int)); printf("sizeof(long) = %d\n",(int)sizeof(long)); printf("sizeof(long long) = %d\n",(int)sizeof(long long)); printf("sizeof(float) = %d\n",(int)sizeof(float)); printf("sizeof(double) = %d\n",(int)sizeof(double)); return 0; } While it compiles fine on Win32 (command line: cl main.c), it does not using the Win64 compiler ("c:\Program Files(x86)\Microsoft Visual Studio 9.0\VC\bin\amd64\cl.exe" main.c). Specifically, it sais "error LNK2019: unresolved external symbol printf referenced in function main". As far as I understand this, it can not link to printf, right? Obviously, I have Microsoft Visual C++ Compiler 2008 (Standard enu) x86 and x64 installed and am using the 64-bit flavor of Windows (7). What is the problem here?

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  • going reverse in a for loop?

    - by sil3nt
    Hello there, Basically i got this for loop and i want the number inputed (eg. 123) to be printed out in reverse, so "321". so far it works fine and prints out the correct order when the for loop is for(i = 0; i<len ; i++) but i get an error when i try to print it in reverse?. Whats going wrong? #include <stdio.h> #include <string.h> void cnvrter(char *number); int main(){ char number[80]; printf("enter a number "); gets(number); cnvrter(number); return 0; } void cnvrter(char *number){ char tmp[80]; int i = 0,len = 0; int cnvrtd_digit = 0; len = strlen(number); printf("\nsize of input %d\n",len); for(i = len; i>len ; i--){ if ( ( number[i] >= '0' ) && ( number[i]<='9' ) ){ tmp[0] = number[i]; sscanf(tmp,"%d",&cnvrtd_digit); } printf("%d\n",cnvrtd_digit); } }

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  • Flex (Lex, not actionscript or w/e) Error

    - by incrediman
    I'm totally new to flex. I'm getting a build error when using flex. That is, I've generated a .c file using flex, and, when running it, am getting this error: 1>lextest.obj : error LNK2001: unresolved external symbol "int __cdecl isatty(int)" (?isatty@@YAHH@Z) 1>C:\...\lextest.exe : fatal error LNK1120: 1 unresolved externals here is the lex file I'm using (grabbed from here): /*** Definition section ***/ %{ /* C code to be copied verbatim */ #include <stdio.h> %} /* This tells flex to read only one input file */ %option noyywrap %% /*** Rules section ***/ /* [0-9]+ matches a string of one or more digits */ [0-9]+ { /* yytext is a string containing the matched text. */ printf("Saw an integer: %s\n", yytext); } . { /* Ignore all other characters. */ } %% /*** C Code section ***/ int main(void) { /* Call the lexer, then quit. */ yylex(); return 0; } As well, why do I have to put a 'main' function in the lex syntax code? What I'd like is to be able to call yylex(); from another c file.

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  • 'strcpy' error and warning

    - by Leejo
    I'm getting a 'strcpy' error and warning for the following lines: _tcscpy(strCommandLine,_T("MyProgram.exe /param1")); _tcscpy(strApplicationName,_T("MyProgram.exe")); Not sure why I'm getting a 'strcpy' error or warning since I'm not using 'strcpy'. The only lines related to this is: LPCTSTR strApplicationName; LPTSTR strCommandLine; _tcscpy(strCommandLine,_T("MyProgram.exe /param1")); //warning is on this line _tcscpy(strApplicationName,_T("MyProgram.exe")); //error is on this line The output is: 1c:\documents and settings\X.X\my documents\sandbox\sample.cpp(52) : warning C4996: 'strcpy': This function or variable may be unsafe. Consider using strcpy_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1 c:\program files\microsoft visual studio 8\vc\include\string.h(74) : see declaration of 'strcpy' 1c:\documents and settings\X.X\my documents\sandbox\sample.cpp(53) : error C2664: 'strcpy' : cannot convert parameter 1 from 'LPCTSTR' to 'char *' 1 Conversion loses qualifiers Any ideas on what this could means? These are my headers: iostream windows.h stdio.h tchar.h winnt.h

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  • program that writes the even and odd numbers

    - by user292489
    enter code herei was writting a program that can read a set of numbers file called dog.txt; and also writes to two file separating odd and even. i was able to compile my program however, the output expected is not the same which was supposed to be even numbers in one file called EVEN, odd numbers in file odd. #include <stdio.h> #include <stdlib.h> int main(int argc, char *argv[]) { int i; int even,odd; int num; if (argc != 4) { printf("Usage: executable in_file output_file\n"); exit(0); } FILE *dog = fopen(argv[1], "r"); FILE *feven= fopen(argv[2], "w"); FILE *fodd= fopen (argv[3], "w"); while (fscanf(dog, "%d", &num) != EOF) { if (0==i%2){ i++; printf("even= %d\n", num); } else if(i!=0){ i++; printf("odd= %d\n", num); } } fclose(feven); fclose(fodd); fclose(dog); return 0; } output: even= 1 odd= 2 even= 34 odd= 44 even= 66 odd= 78 even= 94 odd= 21 even= 23 odd= 54 even= 44 odd= 65 even= 78 odd= 68 even= 92

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  • Printing double variable contents

    - by Adil
    I tried following code snippet and output is surprising me: #include <stdio.h> #include <math.h> int main() { double num; unsigned char ch; ch = 19; num = 1.0E+20 ; num += ch * 1.0E+18; printf("E18 = %lf \n",num); printf("E18 = %e \n",num); num = 11.0E+21 ; num += ch * 1.0E+19; printf("E19 = %lf <------\n",num); printf("E19 = %e <------\n",num); num = 11.0E+22 ; num += ch * 1.0E+20; printf("E20 = %lf\n",num); printf("E20 = %e\n",num); num = 11.0E+23 ; num += ch * 1.0E+21; printf("E21 = %lf\n",num); printf("E21 = %e\n",num); num = 11.0E+24 ; num += ch * 1.0E+22; printf("E22 = %lf <------\n",num); printf("E22 = %e <------\n",num); return 0; } The output of the program: E18 = 119000000000000000000.000000 E18 = 1.190000e+20 E19 = 11190000000000000524288.000000 <------ E19 = 1.119000e+22 <------ E20 = 111900000000000001048576.000000 E20 = 1.119000e+23 E21 = 1119000000000000044040192.000000 E21 = 1.119000e+24 E22 = 11189999999999999366660096.000000 <------ E22 = 1.119000e+25 <------ Why the data corrupted when printed while in exponent form its OK

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  • Code Explanation (MPICH)

    - by user243680
    #include "mpi.h" #include <stdio.h> #include <math.h> double f(double a) { return (4.0 / (1.0 + a*a)); } void main(int argc, char *argv[]) { int done = 0, n, myid, numprocs,i; double PI25DT = 3.141592653589793238462643; double mypi, pi, h, sum, x; double startwtime, endwtime; int namelen; char processor_name[MPI_MAX_PROCESSOR_NAME]; MPI_Init(&argc,&argv); MPI_Comm_size(MPI_COMM_WORLD,&numprocs); MPI_Comm_rank(MPI_COMM_WORLD,&myid); MPI_Get_processor_name(processor_name,&namelen); fprintf(stderr,"Process %d on %s\n", myid, processor_name); fflush(stderr); n = 0; while (!done) { if (myid == 0) { printf("Enter the number of intervals: (0 quits) ");fflush(stdout); scanf("%d",&n); startwtime = MPI_Wtime(); } MPI_Bcast(&n, 1, MPI_INT, 0, MPI_COMM_WORLD); if (n == 0) done = 1; else { h = 1.0 / (double) n; sum = 0.0; for (i = myid + 1; i <= n; i += numprocs) { x = h * ((double)i - 0.5); sum += f(x); } mypi = h * sum; MPI_Reduce(&mypi, &pi, 1, MPI_DOUBLE, MPI_SUM, 0, MPI_COMM_WORLD); if (myid == 0) { printf("pi is approximately %.16f, Error is %.16f\n", pi, fabs(pi - PI25DT)); endwtime = MPI_Wtime(); printf("wall clock time = %f\n", endwtime-startwtime); } } } MPI_Finalize(); } Can anyone explain me the above code what it does??I am in lab and my miss has asked me to explain and i dont know what it is.please help

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  • Reading Serial Data From C (OSX /dev/tty)

    - by Jud Stephenson
    I am trying to read data from a bluetooth barcode scanner (KDC300) using C. Here is the code I have so far, and the program successfully establishes a bluetooth connection to the scanner, but when a barcode is scanned, no input is displayed on the screen (Eventually more will be done with the data, but we have to get it working first, right). Here is the program: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <termios.h> #include <sys/ioctl.h> int main (int argc, const char * argv[]) { // define vars int STOP = 0; //char buf[255]; if(argv[1]) { int fd = open("/dev/tty.KDC1", O_RDONLY); if(fd == -1) { printf("%s", strcat("Unable to open /dev/tty.", argv[1])); } int res; while(STOP == 0) { while((res = read(fd,buf,255)) == 0); { if(res > 0) { buf[res]=0; printf("%s:%d\n", buf, res); if(buf[sizeof(buf)]=='\n') break; } } } } return 0; } If anyone has any ideas, I am at a loss on this so far. If it is any help, I can run screen /dev/tty.KDC1 and any barcodes scanned on the scanner appear in the terminal, I just can't do anything with the data. Jud

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  • Writing re-entrant lexer with Flex

    - by Viet
    I'm newbie to flex. I'm trying to write a simple re-entrant lexer/scanner with flex. The lexer definition goes below. I get stuck with compilation errors as shown below (yyg issue): reentrant.l: /* Definitions */ digit [0-9] letter [a-zA-Z] alphanum [a-zA-Z0-9] identifier [a-zA-Z_][a-zA-Z0-9_]+ integer [0-9]+ natural [0-9]*[1-9][0-9]* decimal ([0-9]+\.|\.[0-9]+|[0-9]+\.[0-9]+) %{ #include <stdio.h> #define ECHO fwrite(yytext, yyleng, 1, yyout) int totalNums = 0; %} %option reentrant %option prefix="simpleit_" %% ^(.*)\r?\n printf("%d\t%s", yylineno++, yytext); %% /* Routines */ int yywrap(yyscan_t yyscanner) { return 1; } int main(int argc, char* argv[]) { yyscan_t yyscanner; if(argc < 2) { printf("Usage: %s fileName\n", argv[0]); return -1; } yyin = fopen(argv[1], "rb"); yylex(yyscanner); return 0; } Compilation errors: vietlq@mylappie:~/Desktop/parsers/reentrant$ gcc lex.simpleit_.c reentrant.l: In function ‘main’: reentrant.l:44: error: ‘yyg’ undeclared (first use in this function) reentrant.l:44: error: (Each undeclared identifier is reported only once reentrant.l:44: error: for each function it appears in.)

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  • C: lseek() related question.

    - by Andrei Ciobanu
    I want to write some bogus text in a file ("helloworld" text in a file called helloworld), but not starting from the beginning. I was thinking to lseek() function. If I use the following code: #include <unistd.h> #include <fcntl.h> #include <sys/stat.h> #include <sys/types.h> #include <stdlib.h> #include <stdio.h> #define fname "helloworld" #define buf_size 16 int main(){ char buffer[buf_size]; int fildes, nbytes; off_t ret; fildes = open(fname, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR); if(fildes < 0){ printf("\nCannot create file + trunc file.\n"); } //modify offset if((ret = lseek(fildes, (off_t) 10, SEEK_END)) < (off_t) 0){ fprintf(stdout, "\nCannot modify offset.\n"); } printf("ret = %d\n", (int)ret); if(write(fildes, fname, buf_size) < 0){ fprintf(stdout, "\nWrite failed.\n"); } close(fildes); return (0); } , it compiles well and it runs without any apparent errors. Still if i : cat helloworld The output is not what I expected, but: helloworld Can Where is "Can" comming from, and where are my empty spaces ? Should i expect for "zeros" instead of spaces ? If i try to open helloworld with gedit, an error occurs, complaining that the file character encoding is unknown.

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  • Pipe overwrites buffer, don't know how to overcome

    - by Kalec
    I use a simple pipe. I read with a while, 1 char at a time, I think every time I read a char I overwrite something #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <sys/wait.h> #include <string.h> int main () { int pipefd[2]; int cpid; char buf[31]; if (pipe(pipefd) == -1) { perror("pipe"); exit(EXIT_FAILURE) } cpid = fork(); if (cpid == -1) P perror("cpid"); exit(EXIT_FAILURE); } if (cpid == 0) { // child reads from pipe close (pipefd[1]); // close unused write end while (read (pipefd[0], &buf, 1)>0); printf ("Server receives: %s", buf); close (pipefd[0])l exit (EXIT_SUCCESS); } else { // parent writes to pipe close (pipefd[0]); // closing unused read end; char buf2[30]; printf("Server transmits: "); scanf ("%s", buf2); write (pipefd[1], buf2, strlen(buf2)+1); close(pipefd[1]); wait(NULL); exit(EXIT_SUCCESS); } return 0; } For example, if I input: "Flowers" it prints F and then ~6 unprintable characters

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  • Call by Reference Function in C

    - by Chad
    Hello everyone, I would just like a push in the right direction here with my homework assignment. Here is the question: (1) Write a C function called input which returns void, this function prompts the user for input of two integers followed by a double precision value. This function reads these values from the keyboard and finds the product of the two integers entered. The function uses call by reference to communicate the values of the three values read and the product calculated back to the main program. The main program then prints the three values read and the product calculated. Provide test results for the input: 3 5 23.5. Do not use arrays or global variables in your program. And here is my code: #include <stdio.h> #include <stdlib.h> void input(int *day, int *month, double *k, double *pro); int main(void){ int i,j; double k, pro; input(&i, &j, &k, &pro); printf("%f\n", pro); return 0; } void input(int *i, int *j, double *k, double *pro){ int x,y; double z; double product; scanf("%d", &x); scanf("%d", &y); scanf("%f", &z); *pro += (x * y * z); } I can't figure out how to reference the variables with pointers really, it is just not working out for me. Any help would be great!

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  • objective-c 2.0 properties and 'retain'

    - by Adam
    Stupid question, but why do we need to use 'retain' when declaring a property? Doesn't it get retained anyway when it's assigned something? Looking at this example, it seems that an object is automatically retained when alloc'ed, so what's the point? #import "Fraction.h" #import <stdio.h> int main( int argc, const char *argv[] ) { Fraction *frac1 = [[Fraction alloc] init]; Fraction *frac2 = [[Fraction alloc] init]; // print current counts printf( "Fraction 1 retain count: %i\n", [frac1 retainCount] ); printf( "Fraction 2 retain count: %i\n", [frac2 retainCount] ); // increment them [frac1 retain]; // 2 [frac1 retain]; // 3 [frac2 retain]; // 2 // print current counts printf( "Fraction 1 retain count: %i\n", [frac1 retainCount] ); printf( "Fraction 2 retain count: %i\n", [frac2 retainCount] ); // decrement [frac1 release]; // 2 [frac2 release]; // 1 // print current counts printf( "Fraction 1 retain count: %i\n", [frac1 retainCount] ); printf( "Fraction 2 retain count: %i\n", [frac2 retainCount] ); // release them until they dealloc themselves [frac1 release]; // 1 [frac1 release]; // 0 [frac2 release]; // 0 ¦output Fraction 1 retain count: 1 Fraction 2 retain count: 1 Fraction 1 retain count: 3 Fraction 2 retain count: 2 Fraction 1 retain count: 2 Fraction 2 retain count: 1 Deallocing fraction Deallocing fraction This is driving me crazy!

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  • advanced Visual Studio kung-fu test -- Calling functions from the Immediate Window during debugging

    - by kizzx2
    I see some related questions have been asked, but they're either too advanced for me to grasp or lacking a step-by-step guide from start to finish (most of them end up being insider talk of their own experiment results). OK here it is, given this simple program: #include <stdio.h> #include <string.h> int main() { FILE * f; char buffer[100]; memset(buffer, 0, 100); fun(); f = fopen("main.cpp", "r"); fread(buffer, 1, 99, f); printf(buffer); fclose(f); return 0; } What it does is basically print itself (assume file name is main.cpp). Question How can I have it print another file, say foobar.txt without modifying the source code? It has something to do with running it through VS's, stepping through the functions and hijacking the FILE pointer right before fread() is called. No need to worry about leaking resources by calling fclose(). I tried the simple f = fopen("foobar.txt", "r") which gave CXX0017: Error: symbol "fopen" not found Any ideas? Edit I found out the solution accidentally on Debugging Mozilla on Windows FAQ. The correct command to put into the Immediate Window is f = {,,MSVCR100D}fopen("foo.txt", "r") However, it doesn't really answer this question: I still don't understand what is going on here. How to systematically find out the {,,MSVCR100D} part for any given method? I know the MSVCR version changes from system to system. How can I find that out? Could anyone explain the curly brace syntax, especially, what are those two commas doing there? Are there more hidden gems using this syntax?

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  • Using pthread to perform matrix multiplication

    - by shadyabhi
    I have both matrices containing only ones and each array has 500 rows and columns. So, the resulting matrix should be a matrix of all elements having value 500. But, I am getting res_mat[0][0]=5000. Even other elements are also 5000. Why? #include<stdio.h> #include<pthread.h> #include<unistd.h> #include<stdlib.h> #define ROWS 500 #define COLUMNS 500 #define N_THREADS 10 int mat1[ROWS][COLUMNS],mat2[ROWS][COLUMNS],res_mat[ROWS][COLUMNS]; void *mult_thread(void *t) { /*This function calculates 50 ROWS of the matrix*/ int starting_row; starting_row = *((int *)t); starting_row = 50 * starting_row; int i,j,k; for (i = starting_row;i<starting_row+50;i++) for (j=0;j<COLUMNS;j++) for (k=0;k<ROWS;k++) res_mat[i][j] += (mat1[i][k] * mat2[k][j]); return; } void fill_matrix(int mat[ROWS][COLUMNS]) { int i,j; for(i=0;i<ROWS;i++) for(j=0;j<COLUMNS;j++) mat[i][j] = 1; } int main() { int n_threads = 10; //10 threads created bcos we have 500 rows and one thread calculates 50 rows int j=0; pthread_t p[n_threads]; fill_matrix(mat1); fill_matrix(mat2); for (j=0;j<10;j++) pthread_create(&p[j],NULL,mult_thread,&j); for (j=0;j<10;j++) pthread_join(p[j],NULL); printf("%d\n",res_mat[0][0]); return 0; }

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  • CS 50- Pset 1 Mario Program

    - by boametaphysica
    the problem set asks us to create a half pyramid using hashes. Here is a link to an image of how it should look- I get the idea and have written the program until printing the spaces (which I have replaced by "_" just so that I can test the first half of it. However, when I try to run my program, it doesn't go beyond the do-while loop. In other words, it keeps asking me for the height of the pyramid and does not seem to run the for loop at all. I've tried multiple approaches but this problem seems to persist. Any help would be appreciated! Below is my code- # include <cs50.h> # include <stdio.h> int main(void) { int height; do { printf("Enter the height of the pyramid: "); height = GetInt(); } while (height > 0 || height < 24); for (int rows = 1; rows <= height, rows++) { for (int spaces = height - rows; spaces > 0; spaces--) { printf("_"); } } return 0; } Running this program yields the following output- Enter the height of the pyramid: 11 Enter the height of the pyramid: 1231 Enter the height of the pyramid: aawfaf Retry: 12 Enter the height of the pyramid:

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  • Compiling C lib and OCaml exe using it, all using ocamlfind

    - by Magnus
    I'm trying to work out how to use ocamlfind to compile a C library and an OCaml executable using that C library. I put together a set of rather silly example files. % cat sillystubs.c #include <stdio.h> #include <caml/mlvalues.h> #include <caml/memory.h> #include <caml/alloc.h> #include <caml/custom.h> value caml_silly_silly( value unit ) { CAMLparam1( unit ); printf( "%s\n", __FILE__ ); CAMLreturn( Val_unit ); } % cat silly.mli external silly : unit -> unit = "silly_silly" % cat foo.ml open Silly open String let _ = print_string "About to call into silly"; silly (); print_string "Called into silly" I believe the following is the way to compile up the library: % ocamlfind ocamlc -c sillystubs.c % ar rc libsillystubs.a sillystubs.o % ocamlfind ocamlc -c silly.mli % ocamlfind ocmalc -a -o silly.cma -ccopt -L${PWD} -cclib -lsillystubs Now I don't seem to be able to use the created library though: % ocamlfind ocamlc -custom -o foo foo.cmo silly.cma /usr/bin/ld: cannot find -lsillystubs collect2: ld returned 1 exit status File "_none_", line 1, characters 0-1: Error: Error while building custom runtime system The OCaml tools are somewhat mysterious to me, so any pointers would be most welcome.

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  • A queue in C using structs and dynamic memory allocation (linked list)

    - by Martin Pugh
    I am tasked with making a queue data structure in C, as a linked list. Our lecturer gave us a large amount of code to implement a stack, but we have to adapt it to create a queue. The code our lecturer gave us ends up not compiling and segfaulting at the exact same point as the code I wrote for the queue. I'm very new to structs, malloc and C in general, so there could be something painfully obvious I've overlooked. Here is the code I am using: #include <stdio.h> #include <stdlib.h> struct node{ int data; //contains the actual data struct node *prev; //pointer to previous node (Closer to front) struct node *next; //pointer to next node (Closer to back) }; typedef struct node *Nodepointer; struct queue{ Nodepointer front; Nodepointer back; }; typedef struct queue *Queuepointer; main(){ Queuepointer myqueue; //create a queue called myqueue init(myqueue); //initialise the queue Nodepointer new = (Nodepointer)malloc(sizeof(struct node)); myqueue->front = new; } int init(Queuepointer q){ q = (Queuepointer)malloc(sizeof(struct queue)); q->front = NULL; q->back = NULL; } The idea is that the queue struct 'contains' the first and last nodes in a queue, and when a node is created, myqueue is updated. However, I cannot even get to that part (pop and push are written but omitted for brevity). The code is segfaulting at the line myqueue->front = new; with the following gdb output: Program received signal SIGSEGV, Segmentation fault. 0x08048401 in main () at queue.c:27 27 myqueue->front = new; Any idea what I'm doing wrong?

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  • GDB not breaking on breakpoints set on object creation in C++

    - by Drew
    Hi all, I've got a c++ app, with the following main.cpp: 1: #include <stdio.h> 2: #include "HeatMap.h" 3: #include <iostream> 4: 5: int main (int argc, char * const argv[]) 6: { 7: HeatMap heatMap(); 8: printf("message"); 9: return 0; 10: } Everything compiles without errors, I'm using gdb (GNU gdb 6.3.50-20050815 (Apple version gdb-1346) (Fri Sep 18 20:40:51 UTC 2009)), and compiled the app with gcc (gcc version 4.2.1 (Apple Inc. build 5646) (dot 1)) with the commands "-c -g". When I add breakpoints to lines 7, 8, and 9, and run gdb, I get the following... (gdb) break main.cpp:7 Breakpoint 1 at 0x10000177f: file src/main.cpp, line 8. (gdb) break main.cpp:8 Note: breakpoint 1 also set at pc 0x10000177f. Breakpoint 2 at 0x10000177f: file src/main.cpp, line 8. (gdb) break main.cpp:9 Breakpoint 3 at 0x100001790: file src/main.cpp, line 9. (gdb) run Starting program: /DevProjects/DataManager/build/DataManager Reading symbols for shared libraries ++. done Breakpoint 1, main (argc=1, argv=0x7fff5fbff960) at src/main.cpp:8 8 printf("message"); (gdb) So, why of why, does anyone know, why my app does not break on the breakpoints for the object creation, but does break on the printf line? Drew J. Sonne.

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