Look at the following jewel of code and throw at will your best guess:
What will the output be?

(scroll down for *MY* answer...   :)


/*****************************************************************************
 * g++     -o NULL_dereference.g++     NULL_dereference.cpp
 * xlc++_r -o NULL_dereference.xlc++_r NULL_dereference.cpp
 *****************************************************************************/

#include <iostream>
#include <string.h>

void RunTest(char *AmIaNullPtr);

int main(int argc, char **argv)
{
	char  GoodBoy[] = "I am a GOOD boy.",
	     *BadBoy    = NULL;
	int   Result    = 0;

	RunTest(GoodBoy);
	RunTest(BadBoy);

	return Result;
}

void RunTest(char *AmIaNullPtr)
{
	switch (*AmIaNullPtr)
	{
		case '\0':
			std::cout << "I seem to be NULL" << std::endl;
			break;
		default  :
			std::cout << AmIaNullPtr << std::endl;
			break;
	}
}
/*END*/


Surprise, surprise, if you answered:
"it will blow up",
(like I did)
you are right *IF*:
You compile it and run it under Linux (Ubuntu 10.04 to be precise)
The output will look like:

wiseuser@towplane$ g++     -o NULL_dereference.g++     NULL_dereference.cpp
wiseuser@towplane$ ./NULL_dereference.g++;echo $?
I am a GOOD boy.
Segmentation fault
139
wiseuser@towplane$



But if you however compile it in:
wiseuser@AIXhost$ uname -a
AIX AIXhost 3 5 00CE5B734C00
wiseuser@AIXhost$

Your output will be:
wiseuser@AIXhost$ xlc++_r -o NULL_dereference.xlc++_r NULL_dereference.cpp
wiseuser@AIXhost$ ./NULL_dereference.xlc++_r;echo $?
I am a GOOD boy.
I seem to be NULL
0
wiseuser@AIXhost$


Beats me...   :(
ET