NULL

Defined in header <stddef.h>

Defined in header <string.h>

Defined in header <wchar.h>

Defined in header <time.h>

Defined in header <locale.h>

Defined in header <stdio.h>

1	`#define NULL /implementation-defined/`

Expands into implementation-defined null-pointer constant.

Example

#include <stdlib.h>
  
struct S;
void(*f)() = NULL;
  
int main(void)
{    
    char *ptr = malloc(sizeof(char)*10);
    if (ptr == NULL) exit(EXIT_FAILURE);
    free(ptr);
    ptr = NULL;
  
    int* p = NULL;
    struct S *s = NULL;
  
    return EXIT_SUCCESS;
}

Possible output:

(none)

NULL

Example

See also