_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, _fpclassf <float.h>

For more compatibility and conformance information, see Compatibility.

See also

Floating-Point Support
isnan, _isnan, _isnanf
fpclassify