2.13.3.2 free

Declaration:

void free(void *ptr);

Deallocates the memory previously allocated by a call to callocmalloc, or realloc. The argument ptr points to the space that was previously allocated. If ptrpoints to a memory block that was not allocated with callocmalloc, or realloc, or is a space that has been deallocated, then the result is undefined.

No value is returned.