isunordered

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

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.

Parameters

Return value

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

Example

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

isunordered(NAN,1.0) = 1
isunordered(1.0,NAN) = 1
isunordered(NAN,NAN) = 1
isunordered(1.0,0.0) = 0

References

• C11 standard (ISO/IEC 9899:2011):
  • 7.12.14.6 The isunordered macro (p: 261)
  • F.10.11 Comparison macros (p: 531)
• C99 standard (ISO/IEC 9899:1999):
  • 7.12.14.6 The isunordered macro (p: 242)

See also