Preprocessing ##

Hans-Peter Diettrich <DrDiettrich1@netscape.net>
Sat, 13 May 2017 08:49:36 +0200

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Preprocessing ## DrDiettrich1@netscape.net (Hans-Peter Diettrich) (2017-05-13)
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From: Hans-Peter Diettrich <DrDiettrich1@netscape.net>
Newsgroups: comp.compilers
Date: Sat, 13 May 2017 08:49:36 +0200
Organization: Compilers Central
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Keywords: question
Posted-Date: 14 May 2017 21:21:48 EDT

How is the C preprocessor assumed to handle the ## concatenation operator?


In the Windows headers I found macros like
      #define foo(x) bar(##baz(x))
where an expansion into ... (baz ... doesn't make sense, because "(baz"
is not a valid preprocessor token. Can somebody explain the meaning and
handling of such constructs?


DoDi [I would guess that some macro between ( and ## expanded to
nothing. Or it could just be one of those text editing errors. -John]



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