Can I compress an if statement using linq in C#?

Question

In sql, I can make an if statement like the following If MY_STATE in (1,2,3,4)

In C# I have to type if(MY_STATE == STATE.CT || MY_STATE == STATE.MA || MY_STATE == ST

Answer 1

You could use an extension method:

public static class ExtensionMethods
{
    public static bool EqualsAny<T>(this T comparer, params T[] values)
    {
        foreach (T t in values)
            if (comparer.Equals(t))
                return true;

        return false;
    }
}

and use it like:

if (myState.EqualsAny(State.CT, State.MA, State.VA, State.RI)) 
{
    // ...
}

Answer 2

You want to use Contains, which maps onto the SQL IN. I'm assuming State is an enum and stored as an integer.

var states = new int[] { (int)State.CT, (int)State.MA, (int)State.VA, (int)State.RI };

var query = db.States.Where( s => states.Contains( s.State ) );

Answer 3

You could write your own extension method to do that:

static bool IsOneOf<T>(this T value, params T[] set)
{
    return set.Contains(value);
}

Usage: MY_STATE.IsOneOf(STATE_A, STATE_B, STATE_C)

(It's slower at runtime, though. It has to create a temporary array and all parameters to IsOneOf have to be evaluated)

Answer 4

You could do something like:

    enum MyEnum
    {
        A, B, C, D
    }

    // ...
    MyEnum e = MyEnum.A;
    if (new []{ MyEnum.A, MyEnum.B }.Contains(e))
       Console.WriteLine("Yeah!");

Answer 5

In c++ I would use the switch statement.

switch (MY_STATE) {
  case STATE.CT:
  case.STATE.MA:
  case.STATE.VA:
  case.STATE.RI:
    ....
    break;
}

just jotted it down from memory. So you might correct some syntax issues.

Answer 6

if (new [] {State.CT, State.MA, State.VA, State.RI}.Contains(myState)) {
  // There you go
}