关于方法中的形参out

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication7
{
    class Program
    {
        static void Main(string[] args)
        {
            int sum1=100;
            int result = Test(out sum1);
            Console.WriteLine("numbere={0}  result={1}", sum1, result);//结果显示：numbere=11  result=200
            Console.ReadKey();
        }
        public static int Test(out int a)//如果定义了out，则必须在下面的方法体中先定义a的值
        {
            a = 10;
            a = a + 1;
            return 200;
        }
    }
}