帮忙分析下

Question

            private string str = "Class1.str";
            private int i = 0;
            static void StringConvert(string str)
            {
                str = "string being converted.";
            }
            static void StringConvert(Class1 c)
            {
                c.str = "string being converted.";
            }
            static void Add(int i)
            {
                i++;
            }
            static void AddWithRef(ref int i)
            {
                i++;
            }
            static void Main()
            {
                int i1 = 10;
                int i2 = 20;
                string str = "str";
                Class1 c = new Class1();
                Add(i1);
                AddWithRef(ref i2);
                Add(c.i);
                StringConvert(str);
                StringConvert(c);
                Console.WriteLine(i1);
                Console.WriteLine(i2);
                Console.WriteLine(c.i);
                Console.WriteLine(str);
                Console.WriteLine(c.str);
                Console.ReadLine();
            }结果：10 
21 
0 
str 
string being converted.
谁能具体解释下怎么得出这5个结果的？ 详细好。

Answer 1

补充下：
         class Class1
        {
            private string str = "Class1.str";
            private int i = 0;
            static void StringConvert(string str)
            {
                str = "string being converted.";
            }
            static void StringConvert(Class1 c)
            {
                c.str = "string being converted.";
            }
            static void Add(int i)
            {
                i++;
            }
            static void AddWithRef(ref int i)
            {
                i++;
            }
            static void Main()
            {
                int i1 = 10;
                int i2 = 20;
                string str = "str";
                Class1 c = new Class1();
                Add(i1);
                AddWithRef(ref i2);
                Add(c.i);
                StringConvert(str);
                StringConvert(c);
                Console.WriteLine(i1);
                Console.WriteLine(i2);
                Console.WriteLine(c.i);
                Console.WriteLine(str);
                Console.WriteLine(c.str);
                Console.ReadLine();
            }
        } 

Answer 2

重点在ref这个关键字上。了解了有ref和没有ref的区别，你就知道为什么产生这样的结果了

Answer 3

有ref的方法，参数传进去出来值就变了，没有的，传进去出来还是原来的值

Answer 4

可参考
http://msdn.microsoft.com/zh-cn/library/14akc2c7.aspx

Answer 5

http://msdn.microsoft.com/zh-cn/library/14akc2c7.aspx