C Pitfalls and Defects Chapter 7 Portability Defects 7.6 Memory Location 0

Memory location 0
The null pointer does not point to any object.Therefore, it is illegal to use a null pointer for any purpose other than assignment or comparison operations.
Strictly speaking, this is not a portability issue: the effects of misusing a null pointer are undefined in all C programs.The easiest way to check for such problems is to move the program to run on a machine that does not allow access to memory location 0.
Reveal how C handles memory address 0:
#include
int main() {
char *p;
p = NULL;
printf("Location 0 contains %d\n", *p);

return 0;
}