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calloc

From cppreference.com
< c‎ | memory
Defined in header <stdlib.h>
void* calloc( size_t num, size_t size );

Allocates memory for an array of num objects of size size and zero-initializes it.

If allocation succeeds, returns a pointer to the lowest (first) byte in the allocated memory block that is suitably aligned for any object type.

If size is zero, the behavior is implementation defined (null pointer may be returned, or some non-null pointer may be returned that may not be used to access storage)

Contents

[edit] Parameters

num - number of objects
size - size of each object

[edit] Return value

Pointer to the beginning of newly allocated memory or NULL if error has occurred. The pointer must be deallocated with free().

[edit] Notes

Due to the alignment requirements, the number of allocated bytes is not necessarily equal to num*size.

[edit] Example

#include <stdio.h>    /* printf             */
#include <stdlib.h>   /* calloc, free, exit */
 
int main () {
 
    /* Allocate an array of four integers. */
    /* Initialize all elements to 0.       */
    int *A = calloc(4,sizeof(int));
    if (A == NULL) {
       printf("calloc() failed in file %s at line # %d", __FILE__,__LINE__);
       exit(1);
    }
 
    /* Print one of the array elements. */
    printf("A[3] = %d\n", A[3]);
 
    /* Deallocate array A. */
    free(A);
    return 0;
}

Output:

A[3] = 0

[edit] See also