传址out

using System;

public class SimpleClass
{
    string str_origin;
    public string PassByReference(out string s)
    {
        s = "cba";                                                                         //必须在方法里进行初始化
        s = s.ToUpper();
        return s;
    }
    public static void Main()
    {
        SimpleClass sc = new SimpleClass();

        sc.PassByReference(out sc.str_origin);
        Console.WriteLine(sc.str_origin);

    }

}