Releases previously allocated memory to heap.
#include <stdlib.h> void _free(void *ptr);
ptr
a pointer to allocated memory
The _free() function releases a previously allocated memory block. The ptr argument should hold an address returned by the memory allocation functions _ calloc(), _malloc(), or _realloc().
Once the memory block pointed to by ptr has been released, it is no longer valid. The ptr variable should not be used to reference memory again until it is assigned a value from the memory allocation functions. A pointer must only be deallocated once.