Questions about malloc()

[Joseph Casey]

Greetings.
I have read that the mistake of calling free(some_ptr) twice on
malloc(some_data) can cause program malfunction. Why is this?
With thanks.
Joseph Casey.

[Dan Pop]

In <%E*****************@read1.cgocable.net> "Method Man" <a@b.c> writes:

Yea, I suppose not. It could return a NULL:

p = free(p);

I just think free()'ing p and setting p = 0 should be handled in one step
since the operations are closely related and it avoids programmer error.

Now, engage your brain and explain what's the point of nullifying p if
you don't also nullify *all* the other pointers currently pointing into
the memory block that is being deallocated.

And if a free() returning a null pointer is what you want, you can
trivially have it:

#define FREE(p) (free(p), (void *)0)

Dan
--
Dan Pop
DESY Zeuthen, RZ group
Email: Da*****@ifh.de
Currently looking for a job in the European Union