#include <malloc.h>
void *calloc(size_t num elems, size_t elem_size) - Allocate an array and initialise all elements to zero .
void free(void *mem address) - Free a block of memory.
void *malloc(size_t num bytes) - Allocate a block of memory.
void *realloc(void *mem address, size_t news i ze) - Reallocate (adjust size) a block of memory.