Question

I know that you are supposed to use 0 instead of NULL in c++ (even though NULL is defined as 0 in C++ most of the time).

Recently I came across some code where 0x0 was used instead, though.

What is the difference?

Answer 1

0x0 is just 0 written in hexadecimal notation. There is no difference between the two:

0₁₆ = 0₁₀ :)

NULL is usually #defined to 0 somewhere and does the same thing.

Answer 2

There is no difference. In C, NULL is often defined to be (void *)0, but in C++ that s not allowed. A few ancient compilers got this wrong, but they really are ancient.

IMO, it s better to use NULL, as it portrays the intent more clearly, and gives you a nice, easy symbol to S&R when your compiler gets updated to C++ 0x, which will include nullptr.

Answer 3

By the way, everyone,

0x0 is hex, as you have all mentioned, but

0 is Octal, not decimal! :-)

ie any number starting with 0 (and not followed by x) is octal:

0 = 0
01 = 1
02 = 2
...
07 = 7
010 = 8
011 = 9
012 = 10
...

:-)

Answer 4

0x0 and 0 represent the same value, so you can use the one that best suits your eye. When we get C++0x, we ll have the keyword nullptr to represent null pointers of any type.

Answer 5

0x0 is just an expression of the value 0 in hexadecimal. I doubt the compiler will care about the difference.

Answer 6

No difference

In my opinion, 0x0 is more explicit.

Some people may confuse 0 with "0"(0x30 -I´ve seen it happen).

Answer 7

Simply put, its a matter of taste. People like to write memory addresses in hexa decimal, so writing NULL as 0x0 would be more classic. For ordinary ones like me, 0 will suffice.

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