isnormal3p
Test for a normal value
Usage
#include <math.h>
int isnormal(real-floating x);
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.
Overview
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 isnormal() macro shall determine whether its argument value is normal (neither zero, subnormal, infinite, nor 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.
Return value
The isnormal() macro shall return a non-zero value if and only if its argument has a normal value.
Errors
No errors are defined.
The following sections are informative.
Examples
None.
Application usage
None.
Rationale
None.
Future directions
None.