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Re: Concatenated if and preprocessor

From Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups comp.lang.c
Subject Re: Concatenated if and preprocessor
Date 2025-03-13 14:37 -0700
Organization A noiseless patient Spider
Message-ID <868qp8txwz.fsf@linuxsc.com> (permalink)
References <vquuhg$34o8d$2@dont-email.me>

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pozz <pozzugno@gmail.com> writes:

> Consider this code:
>
> if (cond1) {
> ...
> } else if (cond2) {
> ...
> } else if (cond3) {
> ...
> }
>
> I want to activate every single if with a macro preprocessor.  All the
> combinations are possible:  only the first, only the second, only the
> third, the first and second... and so on.
>
> What's the best method to have a clean code that is always compiled
> without errors?

    if ( ..bypass all further tests.. ) {
        // for a "skip all conditional segments" case (if needed)
        ...

 #if TEST_1
    } else if (cond1) {
        ...
 #endif

 #if TEST_2
    } else if (cond2) {
        ...
 #endif

 #if TEST_3
    } else if (cond3) {
        ...
 #endif

    } else {
        // for a "no conditional segment" ran case (if needed)
        ...
    }
    

Having said that, it's hard to imagine a scenario where doing
something like this is the best way to solve the higher level
problem.  It is almost certainly better to rethink the reasoning
that resulted in choosing this scheme, and find a way to avoid it.

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Thread

Concatenated if and preprocessor pozz <pozzugno@gmail.com> - 2025-03-13 16:44 +0100
  Re: Concatenated if and preprocessor David Brown <david.brown@hesbynett.no> - 2025-03-13 16:55 +0100
  Re: Concatenated if and preprocessor scott@slp53.sl.home (Scott Lurndal) - 2025-03-13 16:11 +0000
  Re: Concatenated if and preprocessor James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-03-13 12:07 -0400
  Re: Concatenated if and preprocessor Kaz Kylheku <643-408-1753@kylheku.com> - 2025-03-13 16:30 +0000
  Re: Concatenated if and preprocessor bart <bc@freeuk.com> - 2025-03-13 17:29 +0000
  Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-13 14:37 -0700
    Re: Concatenated if and preprocessor Lynn McGuire <lynnmcguire5@gmail.com> - 2025-03-13 18:25 -0500
      Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-14 09:26 -0700
  Re: Concatenated if and preprocessor James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-03-13 12:19 -0400
  Re: Concatenated if and preprocessor pozz <pozzugno@gmail.com> - 2025-03-14 13:02 +0100
    Re: Concatenated if and preprocessor David Brown <david.brown@hesbynett.no> - 2025-03-14 14:13 +0100
    Re: Concatenated if and preprocessor Dan Purgert <dan@djph.net> - 2025-03-14 13:44 +0000
    Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-14 09:44 -0700
      Re: Concatenated if and preprocessor Richard Harnden <richard.nospam@gmail.invalid> - 2025-03-14 18:15 +0000
        Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-14 13:40 -0700
          Re: Concatenated if and preprocessor Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-03-14 14:10 -0700
            Re: Concatenated if and preprocessor Richard Harnden <richard.nospam@gmail.invalid> - 2025-03-14 21:31 +0000
              Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-14 15:29 -0700
                Re: Concatenated if and preprocessor David Brown <david.brown@hesbynett.no> - 2025-03-15 17:32 +0100
            Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-14 15:57 -0700
              Re: Concatenated if and preprocessor Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-03-14 16:27 -0700
                Re: Concatenated if and preprocessor scott@slp53.sl.home (Scott Lurndal) - 2025-03-15 15:06 +0000
                Re: Concatenated if and preprocessor Tim Rentsch <tr.17687@z991.linuxsc.com> - 2025-03-15 08:49 -0700
                Re: Concatenated if and preprocessor scott@slp53.sl.home (Scott Lurndal) - 2025-03-15 17:28 +0000
            Re: Concatenated if and preprocessor David Brown <david.brown@hesbynett.no> - 2025-03-15 17:28 +0100
        Re: Concatenated if and preprocessor Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-03-15 07:03 +0000
    Re: Concatenated if and preprocessor Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2025-03-14 11:10 -0700
    Re: Concatenated if and preprocessor James Kuyper <jameskuyper@alumni.caltech.edu> - 2025-03-14 23:20 -0400

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