Expert: Narendra - 8/2/2005

Question
float a=.7;
if (a==.7)
printf ("hallo");
else
printf ("bye");


the answer is "bye" ?
why 'a' is not equal to .7
                  ...thanx!


Answer
The problem is that, the float is the representation of floats.
0.7 could be 0.6999999!
So, you should not compare the floats in the traditional way.
You have to keep a precision and use it.
Here is the corrected code which you can try.

#include <stdio.h>

#define PRECISION 0.00001

main()
{
  float a = 0.7;

  if (abs(a - 0.7) <= PRECISION)
     printf("Hello\n");
  else
     printf("Bye\n");
}

This time the answer will be: "Hello".

Hope you understood the reason.