Thread: About NULL subject in C

Hi;
NULL is considered as a pointer right? or its bi-sided, meaning it can be considered as value or as pointer?

For example: I can write

Code:

int *p;
p=NULL; // in this case its not pointing to any addresses!

Also can write like

Code:

int *p;
*p=NULL;

so what's the differences between two cases? in second case also I'm having value NULL which is ofcourse by default its pointer NULL, isnt it? !

thanks!

so what's the differences between two cases?

One case is attempting to set a value to NULL, and one case is attempting to set the pointer to NULL.

Be careful with NULL, in many cases it can act like an int, but it is usually as defined as a ((void *)0), you should never try to use NULL on anything other than a pointer.

Originally Posted by jimblumberg

One case is attempting to set a value to NULL, and one case is attempting to set the pointer to NULL.

Be careful with NULL, in many cases it can act like an int, but it is usually as defined as a ((void *)0), you should never try to use NULL on anything other than a pointer.

So, we can see, NULL is acting like a value called NULL ( 0 in int), and as a pointer pointing to nothing! right?

So, we can see,

Yes, we can see that that original code is crap, you should never use NULL with anything but pointers. Using it for anything else is a very bad practice and may or may not work as you seem to expect it to work.