Makes available for reallocation the area allocated by a previous
    calloc, malloc, or realloc call.

    Format

      #include  <stdlib.h>

      void free  (void *ptr);

1  –  Argument

 ptr

    The address returned by a previous call to malloc, calloc, or
    realloc. If ptr is a NULL pointer, no action occurs.

2  –  Description

    The ANSI C standard defines free as not returning a value;
    therefore, the function prototype for free is declared with
    a return type of void. However, since a free can fail, and
    since previous versions of the C RTL have declared free
    to return an int, the implementation of free does return 0 on
    success and -1 on failure.