Why doesn't free(p) set p to NULL?

Question

Any reasons why this can not be standard behavior of free()?

multiple pointers pointing to the same object:

#include 
#i         


        

Answer 1

If it did, you would have to pass a pointer to a pointer to the function:

int * p = malloc( sizeof( int ));
free( & p );

which I'm sure many people would get wrong.