🚀 go-pugleaf

In article <1996Jan5.094122.16151@sq.com>, msb@sq.com (Mark Brader) writes:

|> Nobuhiko Katayama (nk@lns598.lns.cornell.edu) writes:
|>> is there any portable way to tell whether
|>> long is longer(shorter) than double in preprocessor stage ?

|> I can't think of any way.

|> You *can* use the various characteristics defined in <limits.h> and
|> <float.h>, as explained in section 5.2.4.2 (2.2.4.2), to find out
|> various information about the types.  In particular, if what you
|> really want is to choose whichever of the two types can hold the
|> larger exact integer value, then in practice you need only do:

|> 	#include <limits.h>
|> 	#include <float.h>
|> 	#if LONG_MAX * DBL_EPSILON > 1
|> 		typedef long mytype;
|> 		#define mytype_format "%ld" /* for printf */
|> 	#else
|> 		typedef double mytype;
|> 		#define mytype_format "%f"
|> 	#endif

This doesn't work as floating point numbers aren't allowed in #if
expressions.  It must be written using a runtime check (which will
probably optimized out by the compiler).
-- 
Andreas Schwab                                      "And now for something
schwab@issan.informatik.uni-dortmund.de              completely different"