totn C Functions

C Language: calloc function
(Allocate and Clear Memory Block)

In the C Programming Language, the calloc function allocates a block of memory for an array.

Syntax

The syntax for the calloc function in the C Language is:

void *calloc(size_t num_members, size_t size);

Parameters or Arguments

num_members
The number of elements in the array.
size
The size of the elements in bytes.

Note

  • The block of memory is cleared by setting all bits to zero.

Returns

The calloc function returns a pointer to the beginning of the block of memory. If the block of memory can not be allocated, the calloc function will return a null pointer.

Required Header

In the C Language, the required header for the calloc function is:

#include <stdlib.h>

Applies To

In the C Language, the calloc function can be used in the following versions:

  • ANSI/ISO 9899-1990

calloc Example

Let's look at an example to see how you would use the calloc function in a C program:

/* Example using calloc by TechOnTheNet.com */

/* The size of memory allocated MUST be larger than the data you will put in it */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, const char * argv[])
{
    /* Define required variables */
    char *ptr;
    size_t length;

    /* Define the amount of memory required */
    length = 50;

    /* Allocate and zero memory for our string */
    ptr = (char *)calloc(length, sizeof(char));

    /* Check to see if we were successful */
    if (ptr == NULL)
    {
        /* We were not so display a message */
        printf("Could not allocate required memory\n");

        /* And exit */
        exit(1);
    }

    /* Copy a string into the allocated memory */
    strcpy(ptr, "C calloc at TechOnTheNet.com");

    /* Display the contents of memory */
    printf("%s\n", ptr);

    /* Free the memory we allocated */
    free(ptr);

    return 0;
}

When compiled and run, this application will output:

C calloc at TechOnTheNet.com

Similar Functions

Other C functions that are similar to the calloc function:

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