nan, nanf, nanl

Returns a quiet NaN value.

Syntax

double nan( const char* input );
float nanf( const char* input );
long double nanl( const char* input );

Parameters

input
A string value.

Return value

The nan functions return a quiet NaN value.

Remarks

The nan functions return a floating-point value that corresponds to a quiet (non-signalling) NaN. The input value is ignored. For information about how a NaN is represented for output, see printf, _printf_l, wprintf, _wprintf_l.

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

Requirements

Function	C header	C++ header
nan, nanf, nanl	<math.h>	<cmath> or <math.h>

See also

Math and floating-point support
fpclassify
_fpclass, _fpclassf
isfinite, _finite, _finitef
isinf
isnan, _isnan, _isnanf
isnormal