isless

Defined in header <math.h>

1	`#define isless(x, y) /* implementation defined */`

(since C99)

Determines if the floating point number x is less than the floating-point number y, without setting floating-point exceptions.

Parameters

x	-	floating point value
y	-	floating point value

Return value

Nonzero integral value if x < y, 0 otherwise.

Notes

The built-in operator< for floating-point numbers may raise FE_INVALID if one or both of the arguments is NaN. This function is a "quiet" version of operator<.

Example

#include <stdio.h>
#include <math.h>
  
int main(void)
{
    printf("isless(2.0,1.0)      = %d\n", isless(2.0,1.0));
    printf("isless(1.0,2.0)      = %d\n", isless(1.0,2.0));
    printf("isless(INFINITY,1.0) = %d\n", isless(INFINITY,1.0));
    printf("isless(1.0,NAN)      = %d\n", isless(1.0,NAN));
  
    return 0;
}

Possible output:

isless(2.0,1.0)      = 0
isless(1.0,2.0)      = 1
isless(INFINITY,1.0) = 0
isless(1.0,NAN)      = 0

References

C11 standard (ISO/IEC 9899:2011):
- 7.12.14.3 The isless macro (p: 260)
- F.10.11 Comparison macros (p: 531)
C99 standard (ISO/IEC 9899:1999):
- 7.12.14.3 The isless macro (p: 241)

isgreater (C99)	checks if the first floating-point argument is greater than the second (function)
C++ documentation for `isless`