p=0 and p=NULL making me a boka

[Guest_imported]

hi

please help me.

if p is a pointer, are p = 0; and p = NULL; the same thing??
what do the above statements do?

 

[Zyrenthian]

Yep... they will give you the same end result. I belive somewhere deep down in the code you will find

#define NULL 0


The reason why NULL is used instead of zero is to be more explanitory. Usually NULL is used to signify a pointer.


int isPtrNull(void* ptr)
{
return ptr == NULL;
// which is the same as
return !ptr;
// which is the same as
return ptr == 0;
}

and you can call this like

isPtrNull(nullPtr) // will return true
isPtrNull(NULL) // will return true
isPtrNull(0) // will return true
isPtrNull(non_null_ptr) // will return false

Matt

 

[Nosferatu]

Like Matt said, NULL is used to assing a 0 value to a pointer.
Remember that a pointer holds a memory address.
Assigning 0 to a pointer means literally setting the pointer to point to the address 0000:0000.
[red]Nosferatu[/red]
We are what we eat...
There's no such thing as free meal...

 

[ankan]

And C gurantees that 0000:0000 is never a valid address.
So, in essence u are pointing it to nothing. Ankan.

Please do correct me if I am wrong. s-)