.net written test questions

The answer is written by myself, I don’t know if it’s right
1. Please write the output result (knowledge point: virtual override)

2
Answer:
x=5,y=0
x=6,y=-1

Execution process:
B b=new B();
first call the constructor of A,
then call the virtual method PrintFields() in the constructor of A,
call the overriding method PrintFields();
x=5,y=0;
then call the constructor of B, at this time y= -1;
b.PrintFields();
5+=1;
x=6,y=-1;

3. Investigate the reference type value type and string
Answer: 10 21 0 str sting being converted

        public  class A
        {
    
    
            private string str = "Class1.str";
            private int i = 0;
            public static void StringConvert(string str)
            {
    
    
                str = "string being converted";
            }
            public static void StringConvert(A c)
            {
    
    
                c.str = "string being converted";
            }
            static void Add(int i)
            {
    
    
                i++;
            }
            static void AddWithRef(ref int i)
            {
    
    
                i++;
            }
            static void Main(string[] args)
            {
    
    
                int i1 = 10;
                int i2 = 20;
                string str = "str";
                A c = new A();
                Add(i1);
                AddWithRef(ref i2);
                Add(c.i);
                //由于string类型的不变性，函数内部会创建一块新的内存来存放形参str,不会改变实参str,外部打印的是实参str，所以答案为“str”
                StringConvert(str);
                StringConvert(c);
                Console.WriteLine(i1);
                Console.WriteLine(i2);
                Console.WriteLine(c.i);
                Console.WriteLine(str);
                Console.WriteLine(c.str);
                Console.ReadLine();
            }
        }