练习：字段、属性、方法、构造函数。

    class Program
    {
        static void Main(string[] args)
        {
            Student s = new Student("张三", 100, 100, 100);
            s.SayHello();
            s.ShowScore();
            Console.ReadKey();


            Student zsStudent = new Student("张三", 18, '男', 100, 100, 100);
            zsStudent.SayHello();
            zsStudent.ShowScore();
            Console.ReadKey();


            Student xlStudent = new Student("小兰", 16, '女', 50, 50, 50);
            xlStudent.SayHello();
            xlStudent.ShowScore();
            Console.ReadKey();         
        }
    }

    public class Student
    {
        //字段、属性、方法、构造函数
        //析构函数  构造函数

        /// <summary>
        /// 当程序结束的时候,析构函数才执行,帮助我们释放资源。
        /// GC Garbage Collection
        /// </summary>
        ~Student()
        {
            Console.WriteLine("我是析构函数");
        }


        public Student(string name, int age, char gender, int chinese, int math, int english)
        {
            this.Name = name;
            this.Age = age;
            this.Gender = gender;
            this.Chinese = chinese;
            this.Math = math;
            this.English = english;
        }
        public Student(string name, int chinese, int math, int english):this(name,0,'c',chinese,math,english)
        {
            //this.Name = name;
            //this.Chinese = chinese;
            //this.Math = math;
            //this.English = english;
        }
        public Student(string name, int age, char gender)
        {
            this.Name = name;
            if (age < 0 || age > 100)
            {
                age = 0;
            }
            this.Age = age;
            this.Gender = gender;
        }
        public Student()
        { 
            
        }

        private string _name;
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }
        private int _age;
        public int Age
        {
            get { return _age; }
            set
            {
                if (value < 0 || value > 100)
                {
                    value = 0;
                }
                _age = value;
            }
        }
        private char _gender;
        public char Gender
        {
            get
            {
                if (_gender != '男' && _gender != '女')
                {
                    return _gender = '男';
                }
                return _gender;
            }
            set { _gender = value; }
        }
        private int _chinese;
        public int Chinese
        {
            get { return _chinese; }
            set { _chinese = value; }
        }
        private int _math;
        public int Math
        {
            get { return _math; }
            set { _math = value; }
        }
        private int _english;
        public int English
        {
            get { return _english; }
            set { _english = value; }
        }

        public void SayHello()
        {
            Console.WriteLine("我叫{0},我几年{1}岁了，我是{2}生", this.Name, this.Age, this.Gender);
        }

        public void ShowScore()
        {
            Console.WriteLine("我叫{0}，我的总成绩是{1}，平均成绩是{2}", this.Name, this.Chinese + this.Math + this.English, (this.Chinese + this.Math + this.English) / 3);
        }

    }