free() - free up memory allocated with malloc, calloc or realloc
#include <stdlib.h>
void free (void *ptr)
The free(3) function causes the space pointed to by ptr to be deallocated, that is, made available for further allocation. If ptr is a NULL pointer, no action occurs. Otherwise, if the argument does not match a pointer earlier returned by the calloc(3), malloc(3), or realloc(3) function, or if the space has been deallocated by a call to free(3) or realloc(3), problems may result.
The free(3) function returns no value.
calloc(3)
malloc(3)
realloc(3)