реляционные тесты с плавающей запятой без исключения для NaN (floating-point relational tests without exception for NaN)
Имя (Name)
isgreater, isgreaterequal, isless, islessequal, islessgreater,
isunordered - floating-point relational tests without exception
for NaN
Синопсис (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);
Link with -lm.
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
All functions described here:
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
Описание (Description)
The normal relational operations (like <, "less than") 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.
Возвращаемое значение (Return value)
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.
Ошибки (Error)
No errors occur.
Атрибуты (Attributes)
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() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
Стандарты (Conforming to)
POSIX.1-2001, POSIX.1-2008, C99.
Примечание (Note)
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.
Смотри также (See also)
fpclassify(3), isnan(3)
