Chapter 3 induction of knowledge points and Chapter 3 knowledge points

Chapter 3 induction of knowledge points and Chapter 3 knowledge points

1. Object Initiator

Initialize the object directly when calling the constructor.

 

public class Student{    public string Name;    public int Age;    public bool Gender;}Student stu=new Student{Name="zhangsan",Age=10,Gender=false};

Equivalent:

Student stu=new Student();stu.Name="zhangsan";stu.Age=10;stu.Gender=false;

2. this and base

This is the reference class instance itself.

 

public class Student{  string name;  public Test(string name){this.name=name;}}

Base function: 1. Access the overloaded base class method member from the subclass 2. Call the construction method of the base class

Reference the example in the book:

public class Asset{   public string name;   public virtual decimal Liability{ get { return 0; } }}public class Home : Asset{   public decimal Mortgage;    public override decimal Liability    {        get { return base.Liability + Mortgage; }    }}

3. packing and unpacking

Packing is to convert the value type to the reference type.

Int num = 10;

Object obj = x; // boxed int type

The case is to convert the reference type to the value type.

Object obj = 10;

Int num = (int) obj;

The essence of packing and unpacking is copying: Packing refers to copying a value-type instance to a new object, and disassembling refers to copying the content of the object back to a value-type instance.

 

4. covariant and Inverter

Covariant: Assume that A is A subclass of B. If C <A> can be referenced and converted to C <B>, C is called A covariant class.

IAbc <string> a = ...;

IAbc <object> B =;

IAbc <T> is a covariant class.

Inverter: Assume that A is A subclass of B. If C <B> can be referenced and converted to C <A>, C is called an inverter class.