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 
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Answer 1

Bjarne Stroustrup discussing whether the delete operator should zero its operand. It's not the free() function, but it's a good discussion anyway. Consider points like:

• What would be zeroed out if you said free(p + 1)?
• What if there are two pointers to the memory? Why only set one to null if a dangling reference is still left behind?

He also says it was intended but never happened with operator delete:

C++ explicitly allows an implementation of delete to zero out an lvalue operand, and I had hoped that implementations would do that, but that idea doesn't seem to have become popular with implementers.