fpclassify()

Updated: October 26, 2022

Categorize a floating-point number

Synopsis:

#include <math.h>

#define fpclassify( x ) ...

Arguments:

x
A floating-point value.

Library:

libm
The general-purpose math library.
libm-sve
(QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

Note: Compile your program with the -fno-builtin option to prevent the compiler from using a built-in version of the function.

Description:

The fpclassify() macro categorizes the given value as one of the following:

FP_NORMAL
The value is normal, i.e., not an infinity, subnormal, not-a-number or zero.
FP_SUBNORMAL
The value is subnormal.
FP_ZERO
The value is positive or negative zero.
FP_INFINITE
The value is not representable by the underlying type (positive or negative infinity).
FP_NAN
The value is not-a-number (NaN).

Returns:

The category of the number.

Classification:

C11, POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler Yes
Signal handler Yes
Thread Yes