isunordered

Header: <math.h>

Determines if the floating point numbers x and y are unordered, that is, one or both are NaN and thus cannot be meaningfully compared with each other.

# Declarations

#define isunordered(x, y) /* implementation defined */

(since C99)

# Parameters

# Return value

Nonzero integral value if either x or y is NaN, 0 otherwise.

# Example

#include <math.h>
#include <stdio.h>
 
int main(void)
{
    printf("isunordered(NAN,1.0) = %d\n", isunordered(NAN, 1.0));
    printf("isunordered(1.0,NAN) = %d\n", isunordered(1.0, NAN));
    printf("isunordered(NAN,NAN) = %d\n", isunordered(NAN, NAN));
    printf("isunordered(1.0,0.0) = %d\n", isunordered(1.0, 0.0));
 
    return 0;
}

# See also