using System;

using System.Collections;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    private static readonly IEnumerable<Type> _allowedTypes = new[]

        {

            typeof(string),

            typeof(int)

        };

​

    public static void Main()

    {

        var t1 = "test";

        var t2 = 2;

        var t3 = 3m;

        _allowedTypes.Contains(t1.GetType()).Dump();

        _allowedTypes.Contains(t2.GetType()).Dump();

        _allowedTypes.Contains(t3.GetType()).Dump();

    }

}