CLASS, STRUCT, INTERFACE ThS. Nguyễn Hà Giang 1Nguyen Ha Giang -2009 Content 1. Class definition 2. Constructor & destructor 3. Property 4. Indexer 5. Polymorphism 6. Downcast –Upcast 7. Abstract class –Sealed class 8. Struct 9. Interface 2Nguyen Ha Giang -2009 Class declaration Nguyen Ha Giang -2009 3 [access modifier] class <class_name> [:base class, interfaces…] { // class body } Access modifier public protected internal protected internal private (default) Base class: only one class or not Interface: implement some interfaces Class declaration Nguyen Ha Giang -2009 4 public class Student { // data member … // function member … } Access modifier public No base class Default derive from object (System.Object) Class member Nguyen Ha Giang -2009 5 Class Constructor Properties Indexer Delegate, event Method Field, const, readonly Nested type Constructor • Called when create object • Same class name • Class has default constructor which no parameter • Class has multiple constructor (overloading constructor) Nguyen Ha Giang -2009 6 Constructor • Default constructor •No parameter •Create object when has no any information • Copy constructor •Input parameter is another object •Create new object like input object • Other constructors •One or more parameter •Create new object with some information Nguyen Ha Giang -2009 7 Constructor • Ex Nguyen Ha Giang -2009 8 public class Student { // data member string name; int year; float mark; // function member … } public Student() { name = “Ha Giang"; year = 1978; mark = 5; } public Student(Student st) { name = st.name; year = st.year; mark = st.mark; } public Student(string sname) { name = sname; } Constructor • The private constructor prevents the class from being created Nguyen Ha Giang -2009 9 class Student { // private Student() { } } class Program { static void Main(string[] args) { Student s = new Student(); } } Constructor • Constructor chaining •Call one constructor from another constructor •Usage •base(parameter): call constructor of base class •this(parameter): call a constructor in the current class Nguyen Ha Giang -2009 10 <constructor of class A> : base(list of parameter) <constructor of class A> : this(list of parameter) [...]... { set { } } Write-only property Nguyen Ha Giang - 2009 [modifers] { get { } } Read-only property 24 Property class Employee { // fields private string name; private float salary; // properties public string NAME { get { return name; } set { name = value; } } public float SALARY { get { return salary; } } } Nguyen Ha Giang - 2009 Read... Ha Giang - 2009 22 Property • Provide a flexible mechanism to read, write or compute the values of private fields Getter/Setter method Property Private member Private member private string name private string name - GetName() - SetName(…) Nguyen Ha Giang - 2009 Property: NAME 23 Property • Properties as “smart” fields [modifers] { [ set { } ] [ get { . CLASS, STRUCT, INTERFACE ThS. Nguyễn Hà Giang 1Nguyen Ha Giang -2 009 Content 1. Class definition 2. Constructor & destructor 3 class –Sealed class 8. Struct 9. Interface 2Nguyen Ha Giang -2 009 Class declaration Nguyen Ha Giang -2 009 3 [access modifier] class <class_name> [:base class, interfaces…] { // class body } Access. information Nguyen Ha Giang -2 009 7 Constructor • Ex Nguyen Ha Giang -2 009 8 public class Student { // data member string name; int year; float mark; // function member … } public Student() { name = “Ha Giang& quot;; year