| Standards / Extensions | C or C++ | Dependencies |
|---|---|---|
ISO C |
both |
#include <stdlib.h>
void *calloc(size_t num, size_t size);Reserves storage space for an array of num elements, each of length size bytes. The calloc() function then gives all the bits of each element an initial value of 0.
calloc() returns a pointer to the reserved space. The storage space to which the returned value points is aligned for storage of any type of object.
This function is also available to C applications in free-standing System Programming C (SPC) Facilities applications.
Special behavior for C++: The C++ keywords new and delete are not interoperable with calloc(), free(), malloc(), or realloc().
If successful, calloc() returns the pointer to the area of memory reserved.
⁄* CELEBC01
This example prompts for the number of array entries required
and then reserves enough space in storage for the entries.
If &calloc. is successful, the example prints out each entry;
otherwise, it prints out an error message.
*⁄
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
long * array; ⁄* start of the array *⁄
long * index; ⁄* index variable *⁄
int i; ⁄* index variable *⁄
int num; ⁄* number of entries in the array *⁄
printf( "Enter the number of elements in the array\n" );
scanf( "%i", &num );
⁄* allocate num entries *⁄
if ( (index = array = (long *)calloc( num, sizeof( long ))) != NULL )
{
for ( i = 0; i < num; ++i ) ⁄* put values in array *⁄
*index++ = i; ⁄* using pointer notation *⁄
for ( i = 0; i < num; ++i ) ⁄* print the array out *⁄
printf( "array[ %i ] = %i\n", i, array[i] );
}
else
{ ⁄* out of storage *⁄
printf( "Out of storage\n" );
abort();
}
} Enter the size of the array
array[ 0 ] = 0
array[ 1 ] = 1
array[ 2 ] = 2