Originální popis anglicky:
isgreater, isgreaterequal, isless, islessgreater, isunordered - macros to test a
relation
Návod, kniha: Linux Programmer's Manual
#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);
Link with -lm.
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.
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.
C99
fpclassify(3)
isnan(3)
