Re: #defining a comment

From:
Rolf Magnus <ramagnus@t-online.de>
Newsgroups:
comp.lang.c++
Date:
Mon, 05 Jun 2006 17:40:43 +0200
Message-ID:
<e61j9s$ce0$02$1@news.t-online.com>
hobbes_7_8@yahoo.com wrote:

Hi everybody!

This is basically a pre-processor doubt. I have this very simple
define:

#ifdef NDEBUG
#define QTRACE //
#else
#define QTRACE qDebug()
#endif

... so that the line:

QTRACE << "Foi lido o valor" << *it;

... is expanded to:

qDebug() << "Foi lido o valor" << *it;

... in debug mode, and is expanded to:

// << "Foi lido o valor" << *it;

... in release mode. Unfortunately compilation yields:

main.cpp(17) : error C2143: syntax error : missing ';' before '<<'

... Meaning the pre-processor expanded the macro to absolutely nothing
:( Does anyone know a way to overcome this? I'm developing this on
Visual Studio .NET 2003 but it will run on a HP-UX system, so I can't
rely on any Microsoft extension.


If you're using Qt4, this quote from the documentation might be interesting
for you:

"Both qDebug() and qWarning() are debugging tools. They can be compiled away
by defining QT_NO_DEBUG_OUTPUT and QT_NO_WARNING_OUTPUT during
compilation."

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