isnan.gml

开放源码的编译器open watcom 1.6.0版的源代码

.func isnan
#include <math.h>
int isnan( x );
.funcend
.*
.desc begin
The &func macro determines whether its argument
.arg x
is a NaN.
First, an argument represented in a format wider than its semantic type is
converted to its semantic type. Then determination
is based on the type of the argument.
.np
The argument
.arg x
must be an expression of real floating type.
.desc end
.*
.return begin
The &func macro returns a nonzero value if and only if its argument has
a NaN value.
.return end
.*
.see begin
.im seefpcls isnan
.see end
.*
.exmp begin
#include <math.h>
#include <stdio.h>
.exmp break
void main( void )
{
    printf( "NAN %s a NaN\n",
        isnan( NAN ) ? "is" : "is not" );
}
.exmp output
NAN is a NaN
.exmp end
.*
.class ANSI
.system