_calloc()

Allocates space for a group of objects.

  #include <stdlib.h>
  
  void *_calloc(size_t nmemb, size_t elemsize);    

nmemb

number of elements to allocate

elemsize

size of an element

The _ calloc() function allocates contiguous space for nmemb elements of size elemsize. The space is initialized with all bits zero.

_calloc() returns a pointer to the first byte of the memory area allocated. _ calloc() returns a null pointer ( NULL) if no space could be allocated.

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

int main(void)

{

static char s[] = "woodworking compilers";

char *sptr1, *sptr2, *sptr3;

/* Allocate the memory three different ways... */

/* One: allocate a 30-character block of */

/* uninitialized memory. */

sptr1 = (char *) _malloc(30);

strcpy(sptr1, s);

printf("Address of sptr1: %p\n", sptr1);

/* Two: allocate 20 characters of unitialized memory. */

sptr2 = (char *) _malloc(20);

printf("sptr2 before reallocation: %p\n", sptr2);

strcpy(sptr2, s);

/* Re-allocate 10 extra characters */

/* (for a total of 30 characters). */

/* Note that the memory block pointed to by sptr2 is */

/* still contiguous after the call to _realloc(). */

sptr2 = (char *) _realloc(sptr2, 30);

printf("sptr2 after reallocation: %p\n", sptr2);

/* Three: allocate thirty bytes of initialized memory. */

sptr3 = (char *) _calloc(strlen(s), sizeof(char));

strcpy(sptr3, s);

printf("Address of sptr3: %p\n", sptr3);

puts(sptr1);

puts(sptr2);

puts(sptr3);

/* Release the allocated memory to the heap. */

_free(sptr1);

_free(sptr2);

_free(sptr3);

return 0;

}

Output:

Address of sptr1: 5e5432

sptr2 before reallocation: 5e5452

sptr2 after reallocation: 5e5468

Address of sptr3: 5e5488

woodworking compilers

woodworking compilers

woodworking compilers