C#基本总结

一、为字段赋值的两种方式：1. 通过属性的形式，2. 通过构造函数

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace test
{
    class Program
    {
        static void Main(string[] args)
        {
            Person p = new Person(‘中‘);
            //p.Name = "李四";
            //p.Age = -19;
            //Console.WriteLine(p.Age);
            Console.WriteLine(p.Gender);
            Console.ReadKey();
        }
    }
    class Person
    {
        //字段、属性、函数、构造函数....
        //字段：存储数据
        //属性：保护字段 get set
        //函数：描述对象的行为
        //构造函数：初始化对象，给对象的每个属性进行赋值

        string _name;

        public string Name//张三
        {
            get { return _name; }//去属性的值
            set
            {
                if (value != "张三")
                {
                    value = "张三";
                }
                _name = value;
            }//给属性赋值
        }

        int _age;

        public int Age
        {
            get
            {
                if (_age < 0 || _age > 100)
                {
                    return _age = 18;
                }
                return _age;
            }
            set { _age = value; }
        }

        public char Gender { get; set; }


        /// <summary>
        /// 通过构造函数的形式给字段赋值
        /// </summary>
        /// <param name="gender"></param>
        public Person(char gender)
        {
            if (gender != ‘男‘ && gender != ‘女‘)
            {
                gender = ‘男‘;
            }
            this.Gender = gender;
        }
    }

}

二、3个关键字的总结：new，this，base。

1. new：创建对象，隐藏父类成员

创建对象：Student s = new Student()；

隐藏父类成员：如果使用非重写的方法，需要用关键字new来进行覆盖，具体代码如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            Student s = new Student();
        }
    }
    class Person
    {
        public void SayHello()
        {
            Console.WriteLine("我是人类");
        }
    }
    class Student : Person
    {
        /// <summary>
        /// 如果使用非重写的方法，需要用关键字new来进行覆盖
        /// </summary>
        public new void SayHello()//彻底隐藏了父类的SayHello()
        {
            Console.WriteLine("我是学生");
        }
    }
}

2. this：代表当前类的对象。

   class Teacher
    {
        public string Name { get; set; }
        public int Age { get; set; }
        public char Gender { get; set; }

        public int Chinese { get; set; }
        public int Math { get; set; }
        public int English { get; set; }


        public Teacher(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 Teacher(string name, int age, char gender)
            : this(name, age, gender
                , 0, 0, 0)
        {

        }


        public Teacher(string name, int chinese, int math, int english)
            : this(name, 0, ‘\0‘, chinese, math, english)
        { }


        public void SayHi()
        {
            Console.WriteLine("我叫{0},今年{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);
        }
    }

3. base：调用父类的成员

    class Person
    {
        public void SayHello()
        {
            Console.WriteLine("我是人类");
        }
    }

    class Student : Person
    {
        /// <summary>
        /// 
        /// </summary>
        public new void SayHello()//彻底隐藏了父类的SayHello()
        {
            Console.WriteLine("我是学生");
        }

        public Student GetStudent()
        {
            return this;
        }
        /// <summary>
        /// 调用父类的成员
        /// </summary>
        public void GetPerson()
        {
            base.SayHello();
        }
    }