isless

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isless
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Macro constants
 
Defined in header <math.h>
#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)

See also

checks if the first floating-point argument is greater than the second
(function)