fpclassify.md

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Learn more about: fpclassify	fpclassify	04/05/2018	fpclassify	msvcrt.dll msvcr80.dll msvcr90.dll msvcr100.dll msvcr100_clr0400.dll msvcr110.dll msvcr110_clr0400.dll msvcr120.dll msvcr120_clr0400.dll ucrtbase.dll	HeaderDef	fpclassify math/fpclassify	fpclassify macro fpclassify function	bf549499-7ff9-4a58-8692-f2d1cb6bab81

fpclassify

Returns the floating-point classification of the argument.

Syntax

int fpclassify(
   /* floating-point */ x
);

int fpclassify(
   float x
); // C++ only

int fpclassify(
   double x
); // C++ only

int fpclassify(
   long double x
); // C++ only

Parameters

x
The floating-point value to test.

Return value

fpclassify returns an integer value that indicates the floating-point class of the argument x. This table shows the possible values returned by fpclassify, defined in <math.h>.

Value	Description
FP_NAN	A quiet, signaling, or indeterminate NaN
FP_INFINITE	A positive or negative infinity
FP_NORMAL	A positive or negative normalized non-zero value
FP_SUBNORMAL	A positive or negative denormalized value
FP_ZERO	A positive or negative zero value

Remarks

In C, fpclassify is a macro; in C++, fpclassify is a function overloaded using argument types of float, double, or long double. In either case, the value returned depends on the effective type of the argument expression, and not on any intermediate representation. For example, a normal double or long double value can become an infinity, denormal, or zero value when converted to a float.

Requirements

Function/Macro	Required header (C)	Required header (C++)
fpclassify	<math.h>	<math.h> or <cmath>

The fpclassify macro and fpclassify functions conform to the ISO C99 and C++11 specifications. For more compatibility information, see Compatibility.

See also

Math and floating-point support
isnan, _isnan, _isnanf