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   islessequal    ( 3 )

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)