fpclassify

2017-06-05

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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 C99 and C++11 specifications. For more compatibility information, see Compatibility.

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