Re: Does the null-pointer-constant occupy storage?

From:

red floyd <no.spam.here@its.invalid>

Newsgroups:

comp.lang.c++.moderated

Date:

Thu, 6 Aug 2009 08:19:12 CST

Message-ID:

<h5dsh9$dq8$1@news.eternal-september.org>

/dev/null wrote:

Consider the following program.

#include <stdio>

const int NULL = 0; // Recommended NULL definition according to The C+
+ Programming Language by Bjarne Stroustrup.

// function that changes NULL.
void foo( void )
{
     int *p = const_cast<int32 *>(&NULL);
     *p = 42;
}

// Print value of NULL.
void print_null( void )
{
     std::cout << NULL;
}

int main( void )
{
     foo();
     print_null();
}

Is this a well-formed C++ program?

No. there is no such header as <stdio>. Use <iostream>.

std::cout is defined in <iostream>.

Also, foo has undefined behavior, because you're attempting to modify
a const value through a non-const pointer.

I think also that print_null may not be well defined because cout isn't
flushed, but I'm not sure about that.

If so, what will it print?

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