C#协变和逆变示例

CovarianceAndContravariance.cs

using System;

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Two the_two = new Two();
            //      协变                       逆变
            One the_one = AcceptOneReturnTwo(the_two);
        }
        public static Two AcceptOneReturnTwo(One one){
            return (Two)one;
        }
    }
    public class One{ }
    public class Two : One{ }
}