NULL Pointer in C.
#include <stdio.h> #include <conio.h> int main () { int b = 34 ; int * pt = & b ; printf ( "The address of b is %d \n " , pt ); int a = 34 ; int * ptr = NULL ; if ( ptr != NULL ) printf ( "The address of a is %d \n " , * ptr ); else { printf ( "The pointer is a null pointer and can not be defrenced" ); } return 0 ; } OUTPUT: The address of b is 6422288 The pointer is a null pointer and can not be defrenced