Comparing a variable to multiple values

Quite often in my code I need to compare a variable to several values :

if ( type == BillType.Bill || type == BillType.Payment || type == BillType.Receipt )
{
  // Do stuff
}

I keep on thinking I can do :

if ( type in ( BillType.Bill, BillType.Payment, BillType.Receipt ) )
{
   // Do stuff
}

But of course thats SQL that allows this.

Is there a tidier way in C#?

You could do with with .Contains like this:

if (new[] { BillType.Receipt, BillType.Bill, BillType.Payment}.Contains(type)) {}

Or, create your own extension method that does it with a more readable syntax

public static class MyExtensions
{
    public static bool IsIn<T>(this T @this, params T[] possibles)
    {
        return possibles.Contains(@this);
    }
}

Then call it by:

if (type.IsIn(BillType.Receipt, BillType.Bill, BillType.Payment)) {}

There's also the switch statement

switch(type) {
    case BillType.Bill:
    case BillType.Payment:
    case BillType.Receipt:
        // Do stuff
        break;
}

Assuming type is an enumeration, you could use the FlagsAttribute:

[Flags]
enum BillType
{
    None = 0,
    Bill = 2,
    Payment = 4,
    Receipt = 8
}

if ((type & (BillType.Bill | BillType.Payment | BillType.Receipt)) != 0)
{
    //do stuff
}

Try using a switch

 switch (type)
    {
        case BillType.Bill:
        case BillType.Payment:

        break;
    }

Try using C# HashSet for list of values. This can be especially useful if you need to compare many values to single set of values.

Try checking out the Strategy Design Pattern (a.k.a. the Policy Design Pattern).

public interface IBillTypePolicy
{
    public BillType { get; }
    void HandleBillType();
}
public class BillPolicy : IBillTypePolicy
{
    public BillType BillType { get { return BillType.Bill; } }

    public void HandleBillType() 
    { 
        // your code here...
    }
}

Here's a great post on how to dynamically resolve the policy from Los Techies.

What about getting an array of all Enums values and iterate through this?

http://maniish.wordpress.com/2007/09/27/iterate-through-enumeration-c/