problem about calloc-Collection of common programming errors

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  unwind
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  Burhan Ali
  c memory-management malloc calloc
  I know this question may be marked as a duplicate of difference between malloc and calloc but still i would like to ask it.i know calloc initilizes the memory block,here my question is not focusussing on that part.my question is the definition of malloc says it allocates a block of memory of specified size.and calloc says it allocates multiple block of memory ,each of the same size.is this allocation of one block of memory and multiple blocks of memory is a real difference between the two?becaus
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  Mehrdad
  c memory-allocation free calloc free-function
  The question is in the title… I searched but couldn’t find anything.Edit:I don’t really see any need to explain this, but because people think that what I’m saying makes no sense (and that I’m asking the wrong questions), here’s the problem:Since people seem to be very interested in the “root” cause of all the problem rather than the actual question asked (since that apparently helps things get solved better, let’s see if it does), here’s the problem:I’m trying to make a D runtime library base
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  skaffman
  c calloc
  This question already has an answer here:determine size of dynamically allocated memory in c11 answersI have this code:TCHAR *sRes; sRes = (TCHAR *) calloc(16384, sizeof(TCHAR)); DWORD dwRes = sizeof(sRes);dwRes is always 8, and of course _tcslen(sRes) is always 0. I am looking for 16384.
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  user1252280
  c malloc calloc
  For my C application I tried to initialize memory. I am aware of the slower calloc, but fortunatelly there is no need to track performance.I need memory space for just one unsigned int element (up to 65535).This is the part of my code that doesn’t work://Declaration unsigned int part1;//Allocation part1 = (unsigned int) calloc (1,sizeof(unsigned int));That throws the compiler warning:warning: cast from pointer to integer of different size[-Wpointer-to-int-cast]Why does the above code doesn’t wor
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  simonc
  c memcpy strlen calloc
  I have some second thoughts about the following C puzzle question. I’m curious what more experience C programmers may think… Have a look at the sample code:char * strdup (const char * s) { char * buf;int len;assert(s != NULL);len = strlen(s);buf = (char *) calloc(len + 1, sizeof(char)); memcpy(buf, s, len); return buf; }The proposed implementation of strdup() above contains a runtime error that may NOT appear consistently with each invocation. Which one of the following accurately describes th
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  nour02
  c memory malloc calloc
  When I alloc memory outside a while loop for example, is it okay to free it inside it ? Are these two codes equivalent ?int* memory = NULL; memory = malloc(sizeof(int)); if (memory != NULL) {memory=10;free(memory); }int* memory = NULL; memory = malloc(sizeof(int)); if (memory != NULL) {memory=10; } free(memory);
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  NomadAlien
  c memory-management calloc
  I’m trying to allocate a block of memory and then copy data into that space. I made this simple program and it doesn’t do what I expect it to do. Could someone please point out my faulty reasoning.Thanks.#include <stdio.h> #include <stdlib.h>void main(void) { int t1 = 11; int t2 = 22; int *bufptr;bufptr = calloc(2, sizeof(int)); if(bufptr == NULL) {fprintf(stderr, “Out of memory, exiting\n”);exit(1); }memcpy(bufptr, &t1, sizeof(int)); memcpy((bufptr+sizeof(int)), &t2, sizeof(
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  blargman
  c string gcc calloc strlen
  Shouldn’t I get an error if my string goes over 9 characters long in this program?// CString.c // 2.22.11#include <stdio.h> #include <stdlib.h> #include <string.h>main() {char *aString = calloc(10, sizeof(char));if (aString == NULL){return 1;}printf(“PLEASE ENTER A WORD: “);scanf(“%s”, aString);printf(“YOU TYPED IN: %s\n”, aString);//printf(“STRING LENGTH: %i\n”, strlen(aString)); }Thanksblargman
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  Yaolong
  c pointers calloc
  I’m trying to understand a c code, (SimpleScalar, bpred.c), there is the thing that confuses me a lot:int *shiftregs;shiftregs = calloc(1, sizeof(int));int l1index, l2index;l1index = 0; l2index = shiftregs[l1index];I delete some code that might not help. After the calloc call, *shiftregs becomes a pointer array? And what is the value of l2index? Thanks a lot!
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  Pierre Gilfriche
  c calloc
  My program works fine in debug mode but when I try it in release, it always crash when arriving when I use a calloc. The weird thing is that I use exactly the same way to write my calloc several times in a row and the crash only occurs the third time…This is a bit of my code for you to get what I mean :#include <stdio.h> #include <math.h> #include <dir.h> #include <stdlib.h>#include “Normes.h” #define EPS 1.0e-14void atimes(int n, float x[], float r[], int itrnsp, int
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  Abhineet
  c calloc dynamic-allocation
  Possible Duplicate:How do I correctly set up, access, and free a multidimensional array in C? I am trying to dynamically allocate memory for a 2D array using calloc. The columns are fixed as 2 so its only the rows that are dynamic.Here is what I have been trying :unsigned int **pts, rows; int main(){//some codepts = (unsigned int **)calloc(2*rows, sizeof (unsigned int **));}//The code to access the array : for(k=1;k<=i;k++) { printf(“\nX%d=”,k); scanf(“%d”,&pts[k][0]); printf(“\nY%d=”,k)
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  mmd
  gcc crash openmp calloc
  I’m trying to debug a program I wrote. I ran it inside gdb and I managed to catch a SIGABRT from inside calloc(). I’m completely confused about how this can arise. Can it be a bug in gcc or even libc??More details: My program uses OpenMP. I ran it through valgrind in single-threaded mode with no errors. I also use mmap() to load a 40GB file, but I doubt that is relevant. Inside gdb, I’m running with 30 threads. Several identical runs (same input&CL) finished correctly, until the problematic
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  Vizzy
  c arrays malloc calloc
  This came up in a project for class. The question may be a little too long winded, but since I don’t really know where exactly the issue could be, it might be useful to draw it out in full.Let’s say we have a structure of the form:typedef struct {char *name;char **friends;int numFriends; } User;And we have some container for the structure:typedef struct {User *users;int db_size; } DB;We also have two functions for managing friends:void makeFriends(char *name1, char *name2, DB *db) {User user1 =
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  JBRPG
  c segmentation-fault pass-by-reference uninitialized calloc
  I am attempting to handle various structures and pointers in C, and I am particularly stumped by uninitialized values even after calloc-ing the arrays using a function calling by referencesome code (The List successfully works without Graph):// Graph43 void initializeGraph (Graph *G){44 if (G == NULL || *G == NULL){45 fprintf (stderr, “Graph failed to initialize. Exit\n”);46 exit(EXIT_FAILURE);47 }48 // We will leave 0th index as dummy data49 // for math-based purposes50 for (i
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  Hallucynogenyc
  c arrays malloc calloc
  I’ve always programmed in Java, which is probably why I’m so confused about this:In Java I declare a pointer:int[] arrayand initialize it or assign it some memory:int[] array = {0,1,0} int[] array = new int[3]Now, in C, it’s all so confusing. At first I thought it was as easy as declaring it:int array[]and initializing it or assigning it some memory:int array[] = {0,1,0} int array[] = malloc(3*sizeof(int)) int array[] = calloc(3,sizeof(int))Unless I’m wrong, all of the above is equivalent Java-C
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  Dave Rager
  calloc
  My code runs fine on my computer and other test VMs I have, but on my customer’s computer, the behavior is undefined. Sometimes, after pressing OK on the MessageBox in _tmain, the compiled exe uses 100% of the CPU and sometimes it bombs out.#include <windows.h> #include <tchar.h> #include <strsafe.h>DWORD GetVS(TCHAR **sGetVS) {DWORD dwSize = 1024; *sGetVS = (TCHAR *) calloc(dwSize,sizeof(TCHAR));// Buffer for the environment variable value.TCHAR *sBuffEnv = (TCHAR *) calloc
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  jramirez
  c malloc calloc
  quick questionCan you use the free() function without having to prior call a malloc ?? ei.void someFunc( void ) {char str[6] = {“Hello”};//some processing here ….free(str); }I get no compiling errors but Does this work or is it correct at all ?Thank you,
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  axeoth
  c malloc fread calloc
  Just wondering what is the soundest way to allocate memory and freading from a file in C.First, an explanation:int32_t longBuffer;Now, when freading in the longBuffer, the code could go as:fread(&longBuffer, sizeof(longBuffer), 1, fd); //version 1 fread(&longBuffer, sizeof(int32_t), 1, fd); //version 2Among the two, I would say that version 1 is more bug-safe, since if the type of longBuffer changes (let’s say to int16_t), one does not have to worry about forgetting to update the fread’s
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  simonc
  c++ memory-management malloc calloc
  I am creating a struct that has a field that is an unordered_map on the heap. When I use new, I can add to it with no problem. But with calloc, I get an error inserting because the bucket size is 0. It works fine after I call reserve. So, when calloc is called on the struct, does the unordered_map constructor not run? I am confused why if it was in a struct that was new-ed, it seems to have a non-zero bucket size. And is there a better way to go about this besides calling the reserve? (I can’t u
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  Jens
  c calloc
  IMO one is enough, why does calloc require to split it into two arguments?
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  Steve Walsh
  c calloc
  I’m trying to write a c program to test how much memory is on my system. I’m planning to run it under various different conditions:With swap enabled With swap disabled and overcommit (/proc/sys/vm/overcommit_memory) set to false With swap disabled and overcommit (/proc/sys/vm/overcommit_memory) set to true Inside a virtual machine running on the systemI am doing this to learn more about how memory allocation behaves at the limits of the system’s real and virtual memory.I’m running this on a mac
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  Arrigo Pierotti
  c parsing strtok calloc
  I’ve got this little source code, made for testing the parsing of a string similar to variable string I need to use in other project#include <stdio.h> #include <stdlib.h> #include <string.h>int main (void) {char string[] = “C-AC-2C-3C-BOB”;char* s;char* hand[3];char* usr;s = (char*) calloc(1, sizeof(char));hand[1] = (char*) calloc(3, sizeof(char));hand[2] = (char*) calloc(3, sizeof(char));hand[3] = (char*) calloc(3, sizeof(char));usr = (char*) calloc(21, sizeof(char));s = strto
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  Fettle
  c calloc
  I’m getting some kind of pointer collision,Basically, in one function I do,a = calloc(1,28); // gives me 0x100100d10Then pretty soon in a subfunction I do,b = calloc(1,16); // gives me 0x100100d20;first address + 28 is 0x0..d2C, ie, extends over the pointer provided in the second calloc…Whats going on here?Pointer values are from printf, not gdb.
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  sh4d0000
  c free mpi calloc
  I’m trying to learn C and MPI, this program calculates the sum of n floats. But I have an error:/home/xx/PRIMO/primo.exe: free(): invalid next size (fast): 0x000000000109bda0 /home/xx/PRIMO/primo.exe: free(): invalid next size (fast): 0x00000000024fada0 Are 2 days that I don’t know which way to turn. Here the Program:#include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include “mpi.h”#define HOST 0 // prototypes void initialize( int argc, char *a
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  Dreamer
  c++ c segmentation-fault calloc
  I have encountered a problem which I don’t understand, the following is my code:#include <iostream> #include <stdio.h> #include <string.h> #include <cstdlib> using namespace std;int main(int argc, char **argv) {char *format = “The sum of the two numbers is: %d”;char *presult;int sum = 10;presult = (char *)calloc(sizeof(format) + 20, 1); //allocate 24 bytessprintf(presult, format, sum); // after this operation, // the length of presult is 33cout << presult <<
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  user837208
  c segmentation-fault calloc dynamic-allocation
  Here is my code:#include <stdio.h> #include <stdlib.h>int main(){ int n=10; char *s= calloc(2,sizeof(char)); sprintf(s,”%d”,n); printf(s); return 0; }The intent is to assing 2 digit number to a (char *). when I run the code, I get segmentation fault. Outout from valgrind is- ==18540== Command: ./test ==18540== ==18540== Conditional jump or move depends on uninitialised value(s) ==18540== at 0x366C06F397: _IO_str_init_static_internal (in /lib64/libc-2.5.so) ==18540== by 0x366C
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  Kitchi
  c memory-management free calloc
  I was writing a code to check if two functions I wrote to allocate and deallocate memory worked. The two functions were essentiallyint createBaseName(char ***imageName, char **groupName, char *name) {*imageName = calloc(BASELINEC, sizeof(char *)); //This is a 2D array (array of str)*groupName = calloc(MINILINE, sizeof(char)); // This is a 1D array (just an str)sprintf(*groupName, “%s_BGr.fbi”, name);for(bb = 0; bb < BASELINEC; bb++) {(*imageName)[bb] = (char *)calloc(MINILINE, sizeof(char));
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  Joel J. Adamson
  c malloc valgrind calloc
  I am trying to trace a segfault with valgrind. I get the following message from valgrind:==3683== Conditional jump or move depends on uninitialised value(s) ==3683== at 0x4C277C5: sparse_mat_mat_kron (sparse.c:165) ==3683== by 0x4C2706E: rec_mating (rec.c:176) ==3683== by 0x401C1C: age_dep_iterate (age_dep.c:287) ==3683== by 0x4014CB: main (age_dep.c:92) ==3683== Uninitialised value was created by a stack allocation ==3683== at 0x401848: age_dep_init_params (age_dep.c:131) ==368

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