isless Macro

Determines if its first argument is smaller than its second.




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


any floating-point number
any floating-point number

Return Value

Determines if x is smaller than y, as if by the expression (x) < (y) only without any invalid floating-point exception should the arguments be unordered (i.e. should one of them be NaN).


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 = 2.0;
  b = isless(x, y);
  printf("That %f is less than %f is %s\n", x, y, b ? "true" : "false");

Example Output

That -5.700000 is less than 2.000000 is true