Question

I have a class which represents a shape. The Shape class has a property called Angle. I want the setter for this property to automatically wrap the value into the range [0,359].

Unfortunately, a simple _Angle = value % 360; only works for positive numbers. In C#, -40 % 360 == -40. Google calc does it the way I want it. The value should be 320.

What’s the most elegant solution in C#?

Here’s the best way I’ve got so far:

     public double Angle {         get { return _Angle; }          set {             if ( value >= 0 ) {                 _Angle = value % 360;             }             else {                 _Angle = value - (360 * ((int)(value / 360) - 1));              }         }     } 

Edit:

Thanks guys, I now have:

     public double Angle {         get { return _Angle; }          set {             _Angle = (value % 360) + ((value < 0) ? 360 : 0);         }     } 

..Which is a lot better 🙂

Answer 1

Although this is for Java, Java also has the same behavior for modulus. (i.e. -40 % 360 == -40).

The below code should return an answer from [0. 360), regardless of the given angle, positive or negative.

public class Mod {     public static int mod(int a, int b)     {         if (a < 0)             return b + (a % b);         else             return a % b;     }      public static void main(String[] args)     {         System.out.println(mod(40, 360));   // 40         System.out.println(mod(-40, 360));  // 320         System.out.println(mod(-400, 360)); // 320     } } 

Note that works when the given angle is past -360.