using System;

public class Student

{

    // 1. [Code] Create an auto-implementated property Name of type string 

    public string Name {get; set;}

    // 2. [Code] Create an auto-implementated property Age of type int 

    public int Age {get; set;}

    // 3. [Code] Create a private field _GPA of type double and a public property GPA

    //    where _GPA should never be negative.

    private double _GPA;

    public double GPA

    {

        get { return _GPA; }

        set 

        { 

            if (value >= 0)

            {

                _GPA = value;

            }

         }

     }

    // 4. [Code] Create the first constructor with no parameters

    public Student ()

    {

    }

    // 5. [Code] Create the second constructor with 3 parameters to set up the 3 properties

    public Student (string name, int age, double gpa)

    {

        name = Name;

        age = Age;

        gpa = GPA;

    }

    // 6. [Code] Method ShowGPA

    //    Input: string strType, where "regular" or "adjusted" values are expected

    //    Output: return a double GPA value, where the return value is (GPA * 1.15) 

    //    when strType equals to "adjusted", otherwise return GPA

    //    Before you returning the GPA value, check whether GPA is greater than 4. If so, return 4.

    public double ShowGPA (string strType)

    {

        if (GPA > 4)

        {

            return 4;

        } else if (strType == "adjusted")

        {

            GPA = GPA * 1.15;

            return GPA;

        } else {

            return GPA;

        }

    }

    // 7. [Code] Method LuckyDraw

    //    Check 

    //    Input: none

    //    Output: return a bool value whether student is lucky or not according to the rules:

    //    (1) sum up the number of characters of student's name and age.

    //    (2) return true if the number is divisible by 4; false, otherwise. (Hint: use %)

    public bool LuckyDraw ()

    {

        int Num = (Name.Length + Age) % 4;

        if (Num == 0)

        {

            return true;

        } else {

            return false;

        }

    }

}

​

public class Program

{

    // Here is a static function

    public static void Function(int i, ref double d)

    {

        Console.WriteLine("Entering CallFunction: i = {0}, d = {1}", i, d);

        i++;

        d++;

        Console.WriteLine("Exiting CallFunction: i = {0}, d = {1}", i, d);

    }

    public static void Main()

    {

        // Here are some initial values

        string strName = "Mary";

        int iAge = 18;

        double dGPA = 3.6;

        // 8. [Code] Create a student object by using the values above.

        Student student1 = new Student();

        student1.Name = "Mary";

        student1.Age = 18;

        student1.GPA = 3.6;

        // 9. [Code] Call ShowGPA("regular"), and display return value

        Console.WriteLine(student1.ShowGPA("regular"));

        // 10. [Code] Call ShowGPA("adjusted"), and display return value

        Console.WriteLine(student1.ShowGPA("adjusted"));

        // 11. [Code] Call LuckyDraw, and display return value

        Console.WriteLine(student1.LuckyDraw());

        Console.WriteLine("=================");

        /// 12. ***[Write your answer in the following comments]***

        Console.WriteLine("Age:{0}, GPA:{1}", iAge, dGPA);

        // What is the output of the code above?

        // ***Answer: Age: 18, GPA = 3.6

        Function(iAge, ref dGPA);

        // 13. ***[Write your answer in the following comments]***

        Console.WriteLine("Age:{0}, GPA:{1}", iAge, dGPA);

        // What is the output of the code above?

        // ***Answer: Age: 18, GPA: 4.14

        // Why ia one variable incremented and the other is not?

        // ***Answer: GPA uses reference which changes the value while Age does not.

    }

}