C # syntax exercise (9): class [1]-access restrictions, methods, fields, and attributes

By default, all classes inherit from system. Object (or object ):

 
Using system; Class myclass1 {} class myclass2: object {} class myclass3: system. object {} class program {static void main () {myclass1 obj1 = new myclass1 (); myclass2 obj2 = new myclass2 (); myclass3 obj3 = new myclass3 (); console. writeline (obj1.tostring (); // myclass1 console. writeline (obj2.tostring (); // myclass2 console. writeline (obj3.tostring (); // myclass3 console. readkey ();}}

  
 

Class access restrictions and abstract classes, seal class:

Using system;/* Internal: used only for the current project class, which is omitted by default * // * public: public class */class myclass1 {} internal class myclass2 {} public class myclass3 {}/* Abstract: only classes that can be inherited and cannot be directly instantiated */abstract class myclass4 {} internal abstract class myclass5 {} public abstract class myclass6 {} // sealed: class sealed class myclass7 {} internal sealed class myclass8 {} public sealed class myclass9 {} class program {static void main () {myclass1 obj1 = new myclass1 (); myclass2 obj2 = new myclass2 (); myclass3 obj3 = new myclass3 ();/* myclass4, myclass5, and myclass6 are abstract classes and cannot be instantiated */myclass7 obj7 = new myclass7 (); myclass8 obj8 = new myclass8 (); myclass9 obj9 = new myclass9 (); console. writeline (obj1.tostring (); // myclass1 console. writeline (obj2.tostring (); // myclass2 console. writeline (obj3.tostring (); // myclass3 console. writeline (obj7.tostring (); // myclass7 console. writeline (obj8.tostring (); // myclass8 console. writeline (obj9.tostring (); // myclass9 console. readkey ();}}
 
   
 

Method access restrictions:

 
Using system; Class myclass {/* Private: Private method used by the class. This is the default */string Method1 () {return "Method1";} private string method2 () {return "method2";}/* protected: method that can be inherited by subclass */protected string method3 () {return "method3" ;}/ * Internal: methods available for the current project */internal string method4 () {return "method4";}/* Public: Public Method */Public String method5 () {return "method5" ;}} class program {static void main () {myclass OBJ = new myclass ();/* due to access level restrictions, neither Method1, method2, or method3 of myclass can access */console. writeline (obj. method4 (); // method4 console. writeline (obj. method5 (); // method5 console. readkey ();}}

  
 

Static Method:

Using system; Class myclass {/* Static Method */public static string fun1 () {return "fun1";} internal static string fun2 () {return "fun2 ";} /* General Method */Public String fun3 () {return "fun3";} internal string fun4 () {return "fun4" ;}} class program {static void main () {/* static method called by Class Name: */console. writeline (myclass. fun1 (); // fun1 console. writeline (myclass. fun2 (); // fun2/* non-static method called through object: */myclass OBJ = new myclass (); console. writeline (obj. fun3 (); // fun3 console. writeline (obj. fun4 (); // fun4 console. readkey ();}}

  
 

Field:

Using system; Class myclass {public int F1;/* fields also have the following differences: public, internal, protected, and private. The default value is private */public static int F2;/* static fields, read/write through the class name */Public const int F3 = 2008;/* constant field, read through the class name, read-only */Public readonly int F4;/* read-only field, read through the object. Only values */Public myclass () {F4 = 2010;} class program {static void main () can be assigned to the object during declaration and in the constructor () {/* You can access F2 and F3 using the class name, But F3 is read-only */console. writeline (myclass. f2); // 0 console. writeline (myclass. f3); // 2008 myclass. f2 = 2009; console. writeline (myclass. f2); // 2009/* You can access F1 and F4 through an object. However, F4 is read-only */myclass OBJ = new myclass (); console. writeline (obj. f1); // 0 console. writeline (obj. f4); // 2010 obj. f1 = 2009; console. writeline (obj. f1); // 2009 console. readkey ();}}

  
 

Attribute:

Using system; Class myclass {private int Myint; Public int myproperty {get {return Myint;} set {If (value> = 0) Myint = value; else Myint = 100 ;}} class program {static void main () {myclass OBJ = new myclass (); obj. myproperty = 2009; console. writeline (obj. myproperty); // 2009 obj. myproperty =-1; console. writeline (obj. myproperty); // 100 console. readkey ();}}

  
 

Read-Only attributes:

 
Using system; Class myclass {private int Myint = 100; Public int myproperty {get {return Myint ;}} class program {static void main () {myclass OBJ = new myclass (); console. writeline (obj. myproperty); // 100 console. readkey ();}}