_isnan
Checks a given double-precision floating-point value for not a number (NAN).
int _isnan( double x );
Parameters
- x
-
Double-precision floating-point value.
The _isnan function tests a given double-precision floating-point value x, returning a nonzero value if x is a not a number (NAN). A NAN is generated when the result of a floating-point operation cannot be represented in Institute of Electrical and Electronics Engineers (IEEE) format. For information about how a NAN is represented for output, see printf.
| Routine | Required header | Compatibility |
|---|---|---|
| _isnan | <float.h> | Windows 95, Windows 98, Windows 98 Second Edition, Windows Millennium 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.
Libraries
All versions of the C run-time libraries.
