islessgreater(3) -- Linux man page

 

NAME

isgreater, isgreaterequal, isless, islessgreater, isunordered - macros to test a relation  

SYNOPSIS

#include <math.h>

int isgreater(x,y);

int isgreaterequal(x,y);

int isless(x,y);

int islessequal(x,y);

int islessgreater(x,y);

int isunordered(x,y);
 

DESCRIPTION

The normal relation operations (like less) will fail if one of the operands is NaN. This will cause an exception. To avoid this, C99 defines these macros. The macros are guaranteed to evaluate their operands only once. The operand can be of any real floating-point type.
isgreater()
determines (x) > (y) without an exception if x or y is NaN.
isgreaterequal()
determines (x) >= (y) without an exception if x or y is NaN.
isless()
determines (x) < (y) without an exception if x or y is NaN.
islessequal()
determines (x) <= (y) without an exception if x or y is NaN.
islessgreater()
determines (x) < (y) || (x) > (y) without an exception if x or y is NaN. This macro is not equivalent to x != y because that expression is true if x or y is NaN.
isunordered()
is true if x or y is NaN and false otherwise.
 

NOTE

Not all hardware supports these functions, and where it doesn't, they will be emulated by macros. This will give you a performance penalty. Don't use these functions if NaN is of no concern for you.  

CONFORMING TO

C99  

SEE ALSO

fpclassify(3), isnan(3)