Re: Q: C macro's for lvalue statements ? Any C marco Guru's out there ?

From: Måns Rullgård (mru_at_kth.se)
Date: 06/28/04

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    Date: Mon, 28 Jun 2004 15:13:10 +0200

    "Gregor Copoix" <logical@xeption.de> writes:

    >> > I have a set of macros that create variable names depending of the content
    >> > of some other define.
    >> > An example (of how it should look like in the end):
    >> > // --------------- cut
    >> > #define BASE_NAME module1
    >> > // the macro(s) which I need help for :-)
    >> > #define MAKE_VARNAME2(base, var,val) int var#_#base = val
    >> > #define MAKE_VARNAME(var, val) MAKE_VARNAME2(BASE_NAME, var, val)
    >> > // the usage example
    >> > MAKE_VARNAME(status, 0);
    >> > // --------------- cut
    >> >
    >> > which should expand to
    >> > int status_module1 = 0;
    >
    >> You need to use the token merging operator (##) rather than stringification
    >> operator (#), like this:
    >
    >> #define MAKE_VARNAME2(base, var,val) int var##_##base = val
    >
    > But this results still in an lvalue error as the concaternated text is a
    > string for the preprocessor.
    > int "var_module1" = 0;
    > and results in an compiler error.
    > I tried both # and ##.

    Then your bug is somewhere else. It should work with ##. 

    -- 
Måns Rullgård
mru@kth.se
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