Pointer that is assigned NULL is called a null pointer or we can say A null pointer is a special pointer that doesn't point to anything. It is a good practice to assign a NULL value to a pointer variable in case you do not have exact address to be assigned.
main ()
{
int *ptr = NULL; // ptr is a null pointer here
printf("The value of ptr is : %x\n", ptr );
}
Use Case To check for a null pointer one can use if statement as follows:
if(ptr) /* succeeds if p is not null */
if(!ptr) /* succeeds if p is null */
Read more at: http://tech.queryhome.com/45285/c-programming-pointers-basic
