Edit

Share via

_fpclass, _fpclassf

  • Article

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

Syntax

C 
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're similar to fpclassify, but return more detailed information about the argument. The _fpclassf function is only available when compiled for the x64 platform.

By default, this function's global state is scoped to the application. To change this behavior, see Global state in the CRT.

Requirements

Function Required header
_fpclass, _fpclassf <float.h>

For more compatibility and conformance information, see Compatibility.

See also

Math and floating-point support
isnan, _isnan, _isnanf
fpclassify