(1) 两者都是按地址传递的，使用后都将改变原来的数值

(2) ref传进去的參数必须在调用前初始化，out不必

(3) ref传进去的參数在函数内部能够直接使用，而out不可

(4) ref传进去的參数在函数内部能够不被改动，但out必须在离开函数体前进行赋值

(5) ref是有进有出，out是仅仅出不进

string outString = "This is the original outString";        Console.WriteLine(outString);        outMethod(out outString);        Console.WriteLine(outString);        string refString = "This is the original ref string";        Console.WriteLine(refString);        refMethod(ref refString);        Console.WriteLine(refString);