Re: classes, strings, learning in VS.NET
From: Peter van Merkerk (merkerk_at_deadspam.com)
Date: 12/02/03
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Date: Tue, 2 Dec 2003 16:24:13 +0100
> > --------- X.h ---------
> > #ifndef X_H
> > #define X_H
> >
> > class X
> > {
> > public:
> > virtual void foo();
> > };
> >
> > #endif
> >
> > When the X.h file is seen once inside a translation unit the next
time
> > it gets included it will skip the definitions and declarations
inside
> > the X.h file. Most experienced C++ programmers will always put
include
> > guards in header files, even when leaving those out would not cause
> > redefinitions errors at that point in time.
>
> Since the OP is using VS, he could merely have
> #pragma once
> at the top of the headers, thus not needing to check #ifdef etc.
Since we are discussing standard C++ here, I prefer to stay as close to
standard C++ as possible. The C++ standard does not specify what a
compiler should do when it encounters #pragma once, other than ignoring
it in case the compiler does not recognize it. Many compilers do not
support this #pragma, and consequently putting #pragma once on top of
the header will not result in the desired behaviour with those
compilers. The solution I proposed should work on any reasonably
conforming compiler.
-- Peter van Merkerk peter.van.merkerk(at)dse.nl
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