6.11.96 isunordered Macro

Determines if its arguments are unordered.

Include

<math.h>

Prototype

int isunordered(floating-point x, floating-point y);

Arguments

x

any floating-point number

y

any floating-point number

Return Value

Returns 1 if its arguments are unordered (i.e. one or both of them are NaN) or 0 if they are not.

Example

See the notes at the beginning of this chapter or section for information on using printf() or scanf() (and other functions reading and writing the stdin or stdout streams) in the example code.

#include <math.h>
#include <stdio.h>

int main(void)
{
  double x, y;
  int b;

  x = -5.7;
  y = nan(NULL);
  b = isunordered(x, y);
  printf("The arguments %f and %f are %s\n\n", x, y, b ? "unordered" : "ordered");
}

Example Output

The arguments -5.700000 and nan are unordered