_fpclass, _fpclassf

Article
2017-12-18

The latest version of this topic can be found at _fpclass, _fpclassf.

Returns a value indicating the floating-point classification of the argument.

Syntax

int _fpclass(   
   double x   
);  
  
int _fpclassf(   
   float x   
); /* x64 only */

Parameters

x
The floating-point value to test.

Return Value

The _fpclass and _fpclassf functions return an integer value that indicates the floating-point classification of the argument x. The classification may have one of the following values, defined in <float.h>.

Value	Description
`_FPCLASS_SNAN`	Signaling NaN
`_FPCLASS_QNAN`	Quiet NaN
`_FPCLASS_NINF`	Negative infinity ( –INF)
`_FPCLASS_NN`	Negative normalized non-zero
`_FPCLASS_ND`	Negative denormalized
`_FPCLASS_NZ`	Negative zero ( – 0)
`_FPCLASS_PZ`	Positive 0 (+0)
`_FPCLASS_PD`	Positive denormalized
`_FPCLASS_PN`	Positive normalized non-zero
`_FPCLASS_PINF`	Positive infinity (+INF)

Remarks

The _fpclass and _fpclassf functions are Microsoft specific. They are similar to fpclassify, but return more detailed information about the argument. The _fpclassf function is only available when compiled for the x64 platform.

Requirements

Function	Required header
`_fpclass`	<float.h>

For more compatibility and conformance information, see Compatibility.

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