Hello Shriramana, On Fri, 15 Jun 2007 09:13:59 +0530 Shriramana Sharma <samjnaa@xxxxxxxxx> wrote: > Hello. > > To prevent header files from being included more than once in the same > translation unit, we use include guards like > > # ifndef FOO_H > # define FOO_H > ... > # endif > > Recently I came to know that I can use simply: > > # pragma once > > instead of the above group of sentences and the desired effect is still > accomplished. > > This leads me to think of two things: > > 1. why use the ifndef-define-endif method when the pragma once method is > simpler and cleaner? > > 2. why should we need to use either method at all? If it is a > universally undesirable behaviour that the same header file is included > in a translation unit more than once, then an intelligent compiler (or > preprocessor) itself can by default take of this, right? > > I understand that to write portable code that compiles on > not-so-intelligent compilers, we may need to do something manually, so > question 2 is answered, but question 1 still stands... #pragma is simply not supported by all pre-processors, is that directive present in any standard at least? Regards, -- wwp
Attachment:
signature.asc
Description: PGP signature
