Forum ‹ C# ‹ Rounding in C#

[mfranzs]

Hey-

I noticed that AS3 and C# round numbers differently.

When using Math.Round in c# on 0.5, it returns 0.

When I use Math.round in AS3 it returns, 1.

It seems to me that AS3 rounds UP 0.5 to 1, but c# rounds 0.5 TOWARDS ZERO to 0.
(AS3 rounded -0.5 to 0 and C# rounded -0.5 to 0 as well);


How can I make C# always round up, or at least make the two act the same?

Thanks!

[Benjaminsen]

Math.Round in C# can be parameterized to act pretty much as you want it to.

More info here: http://www.dotnetperls.com/math-round

Alternatively you could just floor or ceil the number.

[mfranzs]

Ugh, I just gave up and used a custom class

Code: Select all

public double Round(double value)
{
       return Math.Floor(value + 0.5);
}

Thanks for the help though!

[mfranzs]

Okay, ignore that

Do you guys know a way to use bankers rounding / round to evens in as3?

[mfranzs]

Okay... here's what I came up with

Code: Select all

function bankround(r){
   var n=Math.round(r);
   var z=r%1
   if(z==0.5||z==-0.5){
      var x=n%2
      if(x==1||x==-1){
         n--;
      }
   }
   return n;            
}


If you know something more efficient, please let me know ^_^

[siteadmin]

Code: Select all

// Uses an enum to determine rounding method
public int Round(int num, RoundMethod roundmethod = RoundMethod.AwayZero)
{
    if (int % 1 == 0)
    {
        return int;
    }
    else if (int % 1 < 0.5)
    {
        return Math.Floor(int);
    }
    else if (int % 1 > 0.5)
    {
        return Math.Ceiling(int);
    }
    else
    {
        switch(roundmethod)
        {
            case RoundMethod.Down:
                return int - 0.5; break;
            case RoundMethod.Up:
                return int + 0.5; break;
            case RoundMethod.ToZero:
                return int - 0.5 * Math.Sign(int); break;
            case RoundMethod.AwayZero:
                return int + 0.5 * Math.Sign(int); break;
            case RoundMethod.ToEven:
                return int + (int % 2 - 1); break;
            case RoundMethod.ToOdd:
                return int - (int % 2 - 1); break;
        }
    }
}


[mfranzs]

... Uhm....

What does that code do?

[siteadmin]

It uses an enum called RoundMethod to determine rounding behavior.

[mfranzs]

Oh, okay... thanks!