Printing null pointers

**SterlingM** · 03-18-2010

Whenever I print out the value of pointers, they normally print normally (as in an address in hexadecimal). But if I print a null pointer, it only prints 0 and not 0x00etc. The print line is

Code:

cout<<this<<":  ("<<this->previous<<", "<<this->next<<", "<<this->element<<")"<<endl;

I have tried using

Code:

cout<<ios::hex<< //values to print

and also

Code:

cout.setf(ios::hex)
cout<<//line to print

But each time it still only prints a single 0 when the pointer is null. Is this a Linux issue by any chance? Or a code issue? Thanks.

**MK27** · 03-18-2010

A NULL pointer does not point to an address. Traditionally, memory addresses are represented in hexadecimal, which is why you are used to seeing them represented that way.

But NULL is not an address. A NULL pointer does not point to address 0x00. A NULL pointer points to nothing -- hence, it is a NULL pointer. By the standard, NULL is considered equal to 0 (or false -- a legitimate address, even if invalid, is true). Of course, zero in hexadecimal is 0x00, but probably this representation courtesy of cout is intended to disambiguate address 0x00 from NULL (even tho address 0x00 does not exist anyway).

**SterlingM** · 03-18-2010

Ah okay.

Thread: Printing null pointers

Thread Tools

Search Thread

Display

Printing null pointers

Similar Threads

Syntax Error??

First Time Using Linked Lists, Having Trouble Replacing First Node

printing list

Binary Search Trees Part III

Problem with a menu.