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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
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:
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
The normal relational operations (like <, "less than") will fail if
one of the operands is NaN. This will cause an exception. To avoid
this, C99 defines the macros listed below.
These macros are guaranteed to evaluate their arguments only once.
The arguments must be of real floating-point type (note: do not pass
integer values as arguments to these macros, since the arguments will
not be promoted to real-floating types).
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.
For an explanation of the terms used in this section, see
attributes(7).
┌───────────────────────────────┬───────────────┬─────────┐
│Interface │ Attribute │ Value │
├───────────────────────────────┼───────────────┼─────────┤
│isgreater(), isgreaterequal(), │ Thread safety │ MT-Safe │
│isless(), islessequal(), │ │ │
│islessgreater(), isunordered() │ │ │
└───────────────────────────────┴───────────────┴─────────┘
POSIX.1-2001, POSIX.1-2008, C99.
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 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
2016-03-15 ISGREATER(3)
Pages that refer to this page: fpclassify(3), math_error(7)