How to initialize a pointer in c++,

[Old Wolf]

Yes, but these are the "old" C header files wrapped in the std
namespace. C++ has no need for NULL.

They are standard C++ headers. NULL is a part of C++.
Whether there is a "need" for NULL is a matter of opinion.

You could say that C does not need NULL either, you can
type (void *)0 everywhere.

 

[Phlip]

Yes, but these are the "old" C header files wrapped in the std
namespace. C++ has no need for NULL.

All code should clearly state its intent to the reader. if(p) may be fun and
cute, but if(NULL == p) clearly states its intent.

 

[Richard Herring]

All code should clearly state its intent to the reader. if(p) may be fun and
cute, but if(NULL == p) clearly states its intent.

But, depending on what your p actually represents, the ownership model,
etc. etc., one of the following
if (is_a_valid_pointer(p))
if (!has_expired(p))
if (is_allocated(p))
would be clearer still, and also avoids the problem that caused you to
write your comparison the unnatural way round. Where do you draw the
line?

Personally I'd consider if (p) to be a natural idiom of the language,
and therefore perfectly clear and, moreover, concise.