Checks given double-precision floating-point value for not a number (NAN).
int _isnan( double x );
- Double-precision floating-point value.
_isnan returns a nonzero value if the argument x is a NAN; otherwise it returns 0.
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.
|_isnan||<float.h>||Win 98, Win Me, Win NT, Win 2000, Win XP|
For additional compatibility information, see Compatibility in the Introduction.
All versions of the C run-time libraries.