NAME
isnan() — floating-point test for NaN
SYNOPSIS
#include <math.h>
int isnan(
floating-type
x);
DESCRIPTION
The
isnan()
macro determines whether its argument is a NaN.
The argument must be of floating type.
For HP Integrity servers, the argument
can be any floating type. For PA-RISC, the argument must be
either
double
or
float.
The
isnan()
macro implements the
isnan()
functionality recommended by the IEEE-754 standard for
floating-point arithmetic.
The
isnan()
macro replaces the
isnan()
and
isnanf()
functions, which are obsolete and are no longer supported.
USAGE
To use the
isnan()
macro, compile either with the default
-Ae
option or with the
-Aa
and
-D_HPUX_SOURCE
options. Make sure your program includes
<math.h>.
Link in the math library by specifying
-lm
on the compiler or linker command line.
RETURN VALUE
The
isnan()
macro returns a nonzero value if and only if its argument has a NaN value.
The macro raises no floating-point exceptions.
ERRORS
No errors are defined.
EXAMPLES
Take certain actions if
x
is not a NaN:
#include <math.h>
/*...*/
double x;
/*...*/
if (!isnan(x))
/*...*/
STANDARDS CONFORMANCE
isnan(): ISO/IEC C99
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