InterfaceStudy/InterfaceStudy.Examine/考题.md

# 考题

不运行代码，20分钟内，给出程序输出结果(两个数字)

## 请写出下面代码的输出
``` csharp
    public interface I
    {
        void Print();
    }

    public class ClassA : I
    {
        public int i = 1;

        public ClassA()
        {
            ++ i;
        }

        void I.Print()
        {
            Console.WriteLine(i);
        }

        public virtual void Print()
        {
            Console.WriteLine(++i);
        }
    }

    public class ClassB : ClassA, I
    {
        int i = -1;

        public override void Print()
        {
            Console.WriteLine(--i);
        }
    }

    public class ClassC : ClassA
    {
        int i = -1;

        public override void Print()
        {
            Console.WriteLine(--i);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            I i;
            i = new ClassB();
            i.Print();

            i = new ClassC();
            i.Print();
        }
    }

```