neeraj, some of my experiments: ok buying your arguement that null_pointers can have any value other than 0x000000. firstly where does a null_pointer gets its value from.. I mean a NULL has to be defined somewhere ref: http://www.eskimo.com/~scs/C-faq/q5.4.html and found NULL to be defined in stddef.h on my Linux installation. Alright now we can change the value of NULL and if we did, and if as you said the pointer was converted to a null_pointer, it should also get the new value of NULL that we have defined. <code> #include <stdio.h> #define NULL ((void *)0x1) int main() { char *myptr=NULL; struct mystruct { int num; char name[20]; struct mystruct *next; }; long start=(unsigned long)&((struct mystruct *)0L)->num; long end=(unsigned long)&((struct mystruct *)0L)->next; printf("Null pointer:%i\n",myptr); printf("start:%i\n",start); printf("end:%i\n",end); return 0; } </code> here we have the definitions for the NULL pointer being used. Hence, the outputs of printf should change based on what NULL is defined (if your arguement holds). Execute this program and the value of the start and end do not change even though NULL is redefined as someother value. This essentially means that the convertion to null_pointer does not happen. regards, Sharath ===== -Sharath __________________________________________________ Do You Yahoo!? Yahoo! Games - play chess, backgammon, pool and more http://games.yahoo.com/ -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
