#ifdef

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Article #1048

#1048

From: Azeem Kahn
Date: Tue, 05 Dec 1989 23:58

29 lines
1037 bytes


This question deals with the implementation of #ifdef.
Consider the following:

#define VAR

#ifdef VAR
...
...
#else
/*
#endif
*/
#endif

VAR is defined and hence the #else is the inactive segment. Now
should the preprocessor match the #else with the first or the
second #endif? In other words, does the preprocessor have to look
at the lines in the inactive segment for comments, unclosed qoutes
etc. OR should it disregard everything in the inactive segment and
just keep looking for a matching #endif to satisfy the nesting.

I want to know what the standard says about this. I am not interested
in what some systems do and others don't.

Thanks for any info.

-azeem.

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Path: arc1-ca.pugleaf.net!utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!microsoft!azeemk
From: azeemk@microsoft.UUCP (Azeem Kahn)
Newsgroups: comp.std.c
Subject: #ifdef
Keywords: preprocessor, inactive segments
Message-ID: <9326@microsoft.UUCP>
Date: 5 Dec 89 23:58:01 GMT
Organization: Microsoft Corp., Redmond WA
Lines: 29