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Re: Determining the 'type' of a variable, if only its name is given

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Am 15.06.2012 10:51, schrieb John Reye:
> is it possible, to determine the 'type' of a variable, if only its
> name is given.

[snip things about oldish C99]

> Is there any other way, to determine if a variable var is signed or
> unsigned, if sizeof(var) < sizeof(int) ???

with C11's _Generic you may do that, provided your implementation
hasn't extended integer types that are narrower than int,

you can do something horrible like

_Generic(var,
        default: use_the_previous_method(var),

        char:  (CHAR_MAX < UCHAR_MAX),
        char const:  (CHAR_MAX < UCHAR_MAX),
        char volatile:  (CHAR_MAX < UCHAR_MAX),
        char const volatile:  (CHAR_MAX < UCHAR_MAX),
        char _Atomic:  (CHAR_MAX < UCHAR_MAX),
        char const _Atomic:  (CHAR_MAX < UCHAR_MAX),
        char volatile _Atomic:  (CHAR_MAX < UCHAR_MAX),
        char const volatile _Atomic:  (CHAR_MAX < UCHAR_MAX),

        _Bool:  0,
        _Bool const:  0,
        _Bool volatile:  0,
        _Bool const volatile:  0,
        _Bool _Atomic:  0,
        _Bool const _Atomic:  0,
        _Bool volatile _Atomic:  0,
        _Bool const volatile _Atomic:  0,

        signed char:  1,
        signed short: 1,
        signed char const:  1,
        signed short const: 1,
        signed char volatile:  1,
        signed short volatile: 1,
        signed char const volatile:  1,
        signed short const volatile: 1,
        signed char _Atomic:  1,
        signed short _Atomic: 1,
        signed char const _Atomic:  1,
        signed short const _Atomic: 1,
        signed char volatile _Atomic:  1,
        signed short volatile _Atomic: 1,
        signed char const volatile _Atomic:  1,
        signed short const volatile _Atomic: 1,

        unsigned char:  0,
        unsigned short: 0,
        unsigned char const:  0,
        unsigned short const: 0,
        unsigned char volatile:  0,
        unsigned short volatile: 0,
        unsigned char const volatile:  0,
        unsigned short const volatile: 0,
        unsigned char _Atomic:  0,
        unsigned short _Atomic: 0,
        unsigned char const _Atomic:  0,
        unsigned short const _Atomic: 0,
        unsigned char volatile _Atomic:  0,
        unsigned short volatile _Atomic: 0,
        unsigned char const volatile _Atomic:  0,
        unsigned short const volatile _Atomic: 0
        )


 - the case for "char" works since "unsigned char" can't have padding
   bits
 - _Bool is unsigned per definition
 - then for all cases you have to distinguish all qualified types. at
   least as quickly I didn't come up with an idea that would force an
   conversion to an rvalue such that it would drop all qualifiers, and
   wouldn't promote to the rank of "int"

Jens

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Determining the 'type' of a variable, if only its name is given John Reye <jononanon@googlemail.com> - 2012-06-15 01:47 -0700
  Re: Determining the 'type' of a variable, if only its name is given John Reye <jononanon@googlemail.com> - 2012-06-15 01:51 -0700
    Re: Determining the 'type' of a variable, if only its name is given James Kuyper <jameskuyper@verizon.net> - 2012-06-15 08:18 -0400
      Re: Determining the 'type' of a variable, if only its name is given "BartC" <bc@freeuk.com> - 2012-06-15 13:43 +0100
      Re: Determining the 'type' of a variable, if only its name is given Noob <root@127.0.0.1> - 2012-06-15 17:02 +0200
        Re: Determining the 'type' of a variable, if only its name is given Robert Miles <milesrf@Usenet-News.net> - 2012-07-23 23:20 -0500
    Re: Determining the 'type' of a variable, if only its name is given pete <pfiland@mindspring.com> - 2012-06-15 08:21 -0400
    Re: Determining the 'type' of a variable, if only its name is given Jens Gustedt <jens.gustedt@loria.fr> - 2012-06-15 16:37 +0200
      Re: Determining the 'type' of a variable, if only its name is given Ian Collins <ian-news@hotmail.com> - 2012-06-16 09:27 +1200
        Re: Determining the 'type' of a variable, if only its name is given Jens Gustedt <jens.gustedt@loria.fr> - 2012-06-16 09:38 +0200
      Re: Determining the 'type' of a variable, if only its name is given Tim Rentsch <txr@alumni.caltech.edu> - 2012-06-22 20:42 -0700
        Re: Determining the 'type' of a variable, if only its name is given Jens Gustedt <jens.gustedt@loria.fr> - 2012-06-23 14:41 +0200
          Re: Determining the 'type' of a variable, if only its name is given Tim Rentsch <txr@alumni.caltech.edu> - 2012-06-24 10:15 -0700
    Re: Determining the 'type' of a variable, if only its name is given Tim Rentsch <txr@alumni.caltech.edu> - 2012-06-22 20:31 -0700

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