在练习接口的时候提示，并非所有代码路径都有返回值？

C# code

using System;using System.Collections.Generic;using System.Text;namespace 接口练习{    public interface Ivehicle    {        int trumpet();    }    class Bike : Ivehicle    {        public int trumpet()        {            Console.WriteLine("I am bike 玲玲!");        }    }    class Bus : Ivehicle    {        public int trumpet()        {            Console.WriteLine("I am bus 叭叭!");        }    }    class Program    {                  static void Main(string[] args)        {            Bike dc = new Bike();            Bus gc = new Bus();            dc.trumpet();            gc.trumpet();            Console.ReadLine();      }        }    }

错误1“接口练习.Bike.trumpet()”: 并非所有的代码路径都返回值 1420接口练习
错误2“接口练习.Bus.trumpet()”: 并非所有的代码路径都返回值2320接口练习

我哪儿错了？

[解决办法]
将

C# code

class Bike : Ivehicle    {        public int trumpet()        {            Console.WriteLine("I am bike 玲玲!");        }    }    class Bus : Ivehicle    {        public int trumpet()        {            Console.WriteLine("I am bus 叭叭!");        }    }