PROGRAM DOES NOT SEEM TO RECOGNIZE EQUALITY OPERATOR!PLEASE HELP

[ankoump]

I have written an if statement which states that when x == y a task should be carried out.
Now my values are in double and are decimal values the output is that x = 1.51675 and y= 1.51675 so they are the same. but when the statement is not executed and when i subtract y from x just to test the output is very strange its like 2.356exp-09

How can i stop this?

 

[txjump]

post your exact code snippet so we can look for the problem

 

[sskumar]

Hi ankoump,
i tried like this, but it is working fine
#include <iostream.h>
#include <iomanip.h>

void main(void)
{
double x=0.0, y=0.0;
x = 1.51675;
y = 1.51675;

if( (x-y) == 0)
cout<<&quot;Equal&quot;<<endl;
else
cout<<&quot;Not Equal&quot;<<endl;
}

try to use also setprecision() or precision()

can i have the complete code??.

 

[JOLESEN]

Never ever compare 2 floating point values for equality without allowing a little difference (like 0.00001).
/JOlesen

 

[StukA]

As was mentioned, never test floating point values for equality. What you can do is replace as follows:
float err = .001;/*or whatever margin of error is valid for you*/
float x = 1.51675, y= 1.51675;

if ( abs((x - y) < err) ) cout << &quot;Equal&quot;;
if ((x - y) < -err ) cout << &quot;Y > X&quot;;
if ((x - y) > err ) cout << &quot;X > Y&quot;;

And of course the same can be done with <=, >= also.