Question

I need to do some calculations with fractions which result have infinite decimals.
For example:

240/360=0.666666...

The output has infinite decimals and when I multiply this by an integer the result must be an integer. So I’ve coded this way:

result = someInteger * decimal.divide(240/360);

(Try with someInteger = 2,700)
But the result has decimal values and some calculators or even spreadsheets would output an integer result.
How do I get same results in c#?

Thanks

Answer 1

The output has infinite decimals and when I multiply this by an integer the result must be an integer.

That won’t really happen.

What you can do is careful rounding (after the multiplication).

Or instead of

 result = someInteger * decimal.divide(240/360);

you can use

 result = someInteger * 240 / 360;

what’s the problem with that?

When you’re really serious about working with fractions and keeping the precision you’ll need a special type:

struct Rational 
{
  public readonly int Numerator;
  public readonly int Denominator;

  // lots of members, including operators
}

There are libraries and examples for how to do this.

But note that you still won’t be able to represent π exactly.