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;
}
}
}