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Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name.

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Am 05/04/2012 12:35 AM, schrieb John Reye:
> Here's a nice hack for... getting the max value for any unsigned type:
> from "unsigned char" to "unsigned long long":
> 
> #include <stdio.h>
> #include <limits.h>
> 
> #define GET_TYPE_INT_OR_LARGER_0(var) (var & 0)
> 
> #define GET_SHIFT_CHAR_BIT2(var) ((sizeof(var) >= sizeof(int)) ? 0 :
> (CHAR_BIT * (sizeof(int)-sizeof(var))))

> ....

> What do you think?
> 
> Does the macro GET_MAX_UNSIGNED_RVALUE() really create a literal?
> (i.e. something that can be used in #if ... preprocessing)
> Or does it depend on the compiler?

no

- IIRC ternary expressions are not allowed in the preprocessor
- sizeof is not evaluated in the preprocessor

Jens

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Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. John Reye <jononanon@googlemail.com> - 2012-04-23 12:38 -0700
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. Thomas Richter <thor@math.tu-berlin.de> - 2012-04-23 22:08 +0200
    Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. James Kuyper <jameskuyper@verizon.net> - 2012-04-23 16:45 -0400
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. John Reye <jononanon@googlemail.com> - 2012-04-23 13:28 -0700
    Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. James Kuyper <jameskuyper@verizon.net> - 2012-04-23 17:01 -0400
    Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. Malcolm McLean <malcolm.mclean5@btinternet.com> - 2012-05-04 00:30 -0700
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. Ben Pfaff <blp@cs.stanford.edu> - 2012-04-23 13:36 -0700
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. James Kuyper <jameskuyper@verizon.net> - 2012-04-23 17:11 -0400
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. John Gordon <gordon@panix.com> - 2012-04-23 22:03 +0000
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. John Reye <jononanon@googlemail.com> - 2012-05-03 15:35 -0700
    Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. Jens Gustedt <jens.gustedt@loria.fr> - 2012-05-04 09:00 +0200
      Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. James Kuyper <jameskuyper@verizon.net> - 2012-05-04 07:54 -0400
  Re: Generates integer literal of the largest value a variable can hold. Macro takes only variable-name. Tim Rentsch <txr@alumni.caltech.edu> - 2012-05-07 21:40 -0700

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