| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
ISGREATER(3) Linux Programmer's Manual ISGREATER(3)
isgreater, isgreaterequal, isless, islessequal, islessgreater, isunordered -
floating-point relational tests without exception for NaN
#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.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
All functions described here:
_XOPEN_SOURCE >= 600 || _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
or cc -std=c99
The normal relation operations (like <, "less than") 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 operands 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()
determines whether its arguments are unordered, that is, whether at
least one of the arguments is a NaN.
The macros other than isunordered() return the result of the relational
comparison; these macros return 0 if either argument is a NaN.
isunordered() returns 1 if x or y is NaN and 0 otherwise.
No errors occur.
C99, POSIX.1-2001.
Not all hardware supports these functions, and where hardware support isn't
provided, they will be emulated by macros. This will result in a performance
penalty. Don't use these functions if NaN is of no concern for you.
fpclassify(3), isnan(3)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
2010-09-20 ISGREATER(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface