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Returns the status word containing information about the floating-point class.

int _fpclass( 
   double x 



Double-precision floating-point value.

_fpclass returns an integer value that indicates the floating-point class of its argument x. The status word might have one of the following values, defined in Float.h.

Value Description


Signaling NaN


Quiet NaN


Negative infinity ( –INF)


Negative normalized non-zero


Negative denormalized


Negative zero ( – 0)


Positive 0 (+0)


Positive denormalized


Positive normalized non-zero


Positive infinity (+INF)

Function Required header Compatibility



Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium Edition, Windows NT 4.0, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003

For more compatibility information, see Compatibility in the Introduction.