Switch case statement refactoring

Question

I have the following code with switch case statement:

public string IrregularCouponLabel
{
    get
    {
        switch ((ctrl.IrregularCouponFirst ? 10 : 0) + (ctrl.IrregularCouponLast ? 1 : 0))
        {
            case 11: return LocalString.Evaluate("label.Both");
            case 10: return LocalString.Evaluate("label.First");
            case 1: return LocalString.Evaluate("label.Last");
            default: return LocalString.Evaluate("label.None");
        }
    }
}

How should I refactor this code to be more clear and readable or how could I otherwise improve this code snippet?

UPDATE According to valuable answers I have updated the code in the following way,

    public string IrregularCouponLabel
    {
        get
        {
            return LocalString.Evaluate("label." + GetIrregularCouponValue());
        }
    }

    private string GetIrregularCouponValue()
    {
        bool first = ctrl.IrregularCouponFirst;
        bool last = ctrl.IrregularCouponLast;
        bool both = first && last;
        return both  ? "Both" :
               first ? "First" :
               last  ? "Last" :
                        "None";

    }

What do you think about this? Is it readable or not?

Answer 1

You can use an if statement and the conditional operator:

string label;
if (ctrl.IrregularCouponFirst) {
  label = ctrl.IrregularCouponLast ? "label.Both" : "label.First";
} else {
  label = ctrl.IrregularCouponLast ? "label.Last" : "label.None";
}
return LocalString.Evaluate(label);

You can also use only conditional operators. This way of chaining conditional operators checks take a bit of work to grasp the first time, but it's very compact:

return LocalString.Evaluate(
  ctrl.IrregularCouponFirst && ctrl.IrregularCouponLast ? "label.Both" :
  ctrl.IrregularCouponFirst ? "label.First" :
  ctrl.IrregularCouponLast ? "label.Last" :
  "label.None"
);

Answer 2

I'd write something like this:

string labelName;
if (ctrl.IrregularCouponFirst && ctrl.IrregularCouponLast) {
    labelName = "label.Both"
} else if (ctrl.IrregularCouponFirst) {
    labelName = "label.First";
} else if (ctrl.IrregularCouponLast) {
    labelName = "label.Last";
} else {
    labelName = "label.None";
}
return LocalString.Evaluate(labelName);

Answer 3

I'd use enums.

My suggestion presumes you are able to refactor your existing code a bit. If your control can be modified to keep the position value in one property of the following enum type, this will work.

[Flags]
public enum LabelEnum
{
    None = 0,
    First = 1,
    Last = 2,
    Both = 3
}

//....
ctrl.IrregularCoupon = LabelEnum.Both;
// or
ctrl.IrregularCoupon = LabelEnum.First | LabelEnum.Last

labelName = "label." + ctrl.IrregularCoupon.ToString();

This might be off topic, but if you use switch statements for more complex functionality, you should read this before going further. http://sourcemaking.com/refactoring/replace-conditional-with-polymorphism

Answer 4

I think I would store the IrregularCouponFirst and IrregularCouponLast as flag-enums to improve readability.

So first define the enum:

[Flags]
enum Position
{
    None  = 0,
    First = 1,
    Last  = 2,
    Both  = 3
}

Then to keep compatibility with previous code, I'd consider implementing properties for IrregularCouponFirst and IrregularCouponLast like this:

public Position IrregularCouponPosition;

public bool IrregularCouponFirst
{
    get { return _irregularCouponPosition & Position.First != 0; }
    set { _irregularCouponPosition |= Postion.First; }
}

public bool IrregularCouponLast
{
    get { return _irregularCouponPosition & Position.Last != 0; }
    set { _irregularCouponPosition |= Postion.Last; }
}

And finally your switch would look like this:

public string IrregularCouponLabel
{
    get
    {
        switch (ctrl.IrregularCouponPosition)
        {
            case Position.First: return LocalString.Evaluate("label.First");
            case Position.Last: return LocalString.Evaluate("label.Last");
            case Position.Both: return LocalString.Evaluate("label.Both");
            default: return LocalString.Evaluate("label.None");
        }
    }
}

Which is pretty much the same switch you had to begin with. Though I find it a bit more readable now.

Answer 5

I would likely use:

string type="None";
if (false) {
}else if (ctrl.IrregularCouponFirst && ctrl.IrregularCouponLast){type="Both";
}else if (ctrl.IrregularCouponFirst                            ){type="First";
}else if (ctrl.IrregularCouponLast                             ){type="Last";
}
return LocalString.Evaluate("label."+type);

But then there is always:

var types = new Dictionary<int, string> {
    { 0, "None" }
    ,{ 1, "Last" }
    ,{ 10, "First" }
    ,{ 11, "Both" }
};

int key=(ctrl.IrregularCouponFirst ? 10 : 0) + (ctrl.IrregularCouponLast ? 1 : 0);
return LocalString.Evaluate("label."+types[key]);