Shorthand conditional in C# similar to SQL 'in' keyword

Question

In C# is there a shorthand way to write this:

public static bool IsAllowed(int userID)
{
    return (userID == Personnel.JohnDoe || userID == Personnel.JaneDoe ...);
}

Like:

public static bool IsAllowed(int userID)
{
    return (userID in Personnel.JohnDoe, Personnel.JaneDoe ...);
}

I know I could also use switch, but there are probably 50 or so functions like this I have to write (porting a classic ASP site over to ASP.NET) so I'd like to keep them as short as possible.

Answer 1

How about this?

public static class Extensions
{
    public static bool In<T>(this T testValue, params T[] values)
    {
        return values.Contains(testValue);
    }
}

Usage:

Personnel userId = Personnel.JohnDoe;

if (userId.In(Personnel.JohnDoe, Personnel.JaneDoe))
{
    // Do something
}

I can't claim credit for this, but I also can't remember where I saw it. So, credit to you, anonymous Internet stranger.

Answer 2

How about something like this:

public static bool IsAllowed(int userID) {
  List<int> IDs = new List<string> { 1,2,3,4,5 };
  return IDs.Contains(userID);
}

(You could of course change the static status, initialize the IDs class in some other place, use an IEnumerable<>, etc, based on your needs. The main point is that the closest equivalent to the in operator in SQL is the Collection.Contains() function.)