тест на NaN (test for a NaN)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
isnan — test for a NaN
Синопсис (Synopsis)
#include <math.h>
int isnan(real-floating x);
Описание (Description)
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
The isnan() macro shall determine whether its argument value is a
NaN. First, an argument represented in a format wider than its
semantic type is converted to its semantic type. Then
determination is based on the type of the argument.
Возвращаемое значение (Return value)
The isnan() macro shall return a non-zero value if and only if
its argument has a NaN value.
Ошибки (Error)
No errors are defined.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
fpclassify(3p), isfinite(3p), isinf(3p), isnormal(3p),
signbit(3p)
The Base Definitions volume of POSIX.1‐2017, math.h(0p)
