class Program
{
  /*ref是有进有出，out是只出不进*/
  static void Main(string[] args)
  {
    /*作为Out参数传递 传递前可以不初始化*/
    string outString = "This is the outString value";
    Console.WriteLine(outString);
    outMethod(out outString);
    Console.WriteLine(outString);

    /*作为Ref参数传递 传递前必须初始化*/
    string refString = "This is the refString value";
    Console.WriteLine(refString);
    refMethod(ref refString);
    Console.WriteLine(refString);
    Console.ReadLine();

  }
  static bool outMethod(out string str)
  {
    /*作为Out参数传递 传递到方法体后 参数被清空*/
    //Console.WriteLine(str); Use of unassigned out parameter 'str' 
    /*作为Out参数传递 值必须在方法体内赋值*/
    /*作为Out参数传递 返回前值必须初始化*/
    str = "This is the new outString value";
    return true;
  }
  static bool refMethod(ref string str)
  {
    Console.WriteLine(str);
    /*作为Ref参数传递 返回前值可以不初始化*/
    return true;
  }
}