Duhok Polytechnic University Amedi Technical Institute/ IT Dept. Halkawt Rajab Hussain

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1 Duhok Polytechnic University Amedi Technical Institute/ IT Dept. By Halkawt Rajab Hussain

2 Objects and classes: Basics of object and class in C#. Private and public members and protected. Static data and function members. Constructors and their types. Destructors. Operator overloading. Friend function. 1/12/2017 1

3 Basics of object and class in C#. First of all, a class is a group of related methods and variables. A class describes these things, and in most cases, you create an instance of this class, now referred to as an object. Properties are the data contained in the class. Methods are the operations performed on the data. 1/12/2017 2

4 Basics of object and class in C#. Example using System; namespace stdinfo class Student public string name; public int age; public int MarkofEnglish; public int MarkofMath; public int totalmark = 200; double percentage; public int obtainedmarks; void CalculateTotalMarks() obtainedmarks = MarkofEnglish + MarkofMath; void CalculatePercentage() percentage = (double) obtainedmarks / totalmark * 100; double GetPercentage() return percentage; class Program static void Main(string[] args) Student std1 = new Student(); std1.name = "Amar"; std1.age = 20; std1.markofenglish = 90; std1.markofmath = 80; std1.calculatetotalmarks(); std1.calculatepercentage(); Console.WriteLine("0 of 1 years Age got 2% Marks",std1.name, std1.age, std1.getpercentage()); Console.ReadLine(); 1/12/2017 3

5 Basics of object and class in C#. First of all, a class is a group of related methods and variables. A class describes these things, and in most cases, you create an instance of this class, now referred to as an object. Example/ about car class using System; namespace ConsoleApplication1 class Program static void Main(string[] args) Car car; car = new Car("Red"); Console.WriteLine(car.Describe()); car = new Car("Green"); Console.WriteLine(car.Describe()); Console.ReadLine(); class Car private string color; public Car(string color) this.color = color; public string Describe() return "This car is " + Color; public string Color get return color; set color = value; 1/12/2017 4

6 Accessing Modifiers or Accessibility Levels. 1. Public access specifier: There are no restrictions on accessing public members. The class member, that is defined as public can be accessed by other class member that is initialized outside the class. A public member can be accessed from anywhere even outside the namespace. 1/12/2017 5

7 Accessing Modifiers or Accessibility Levels. Example About Public access// using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Public_Access_Specifiers class access // String Variable declared as public public string name; // Public method public void print() Console.WriteLine("\nMy name is " + name); class Program static void Main(string[] args) access ac = new access(); Console.Write("Enter your name:\t"); ac.name = Console.ReadLine(); ac.print(); Console.ReadLine(); 1/12/2017 6

8 2. Private Access Specifier: Access is limited to within the class definition, This is the default access modifier type if none is formally specified. A private method or variable cannot be called outside from the same class. Private access specifier allows a class to hide its member variables and member functions from other functions and objects. Only functions of the same class can access its private members. Even an instance of a class cannot access its private members. 1/12/2017 7

9 Accessing Modifiers or Accessibility Levels. The following example illustrates this: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace Accessppp class A public int x; private int y; public void SetValue( int b) y = b; public int sum() int s = x + y; return s; class Program static void Main(string[] args) A p = new A(); p.x = 10; // p.y=20//error p.setvalue(20); Console.WriteLine(p.sum()); Console.ReadKey(); 1/12/2017 8

10 Accessing Modifiers or Accessibility Levels. 3. Protected Access Specifier: The protected access specifier hides its member variables and functions from other classes and objects. This type of variable or function can only be accessed in child class. It becomes very important while implementing inheritance. 1/12/2017 9

11 Accessing Modifiers or Accessibility Levels. The following example illustrates this: using System; namespace Accessppp class A public int x; private int y; protected int z; public void SetValue(int b, int c ) y = b; z = c; public int sum() int s = x + y + z ; return s; class Program static void Main(string[] args) A p = new A(); p.x = 10; p.setvalue(20,30); Console.WriteLine(p.sum()); Console.ReadKey(); 1/12/

12 Accessing Modifiers or Accessibility Levels. Example. access to protected member via child class using System; namespace Accessppp class A public int x; private int y; protected int z; public void SetValue(int b, int c ) y = b; z = c; public int sum() int s = x + y + z ; return s; class Program: A static void Main(string[] args) Program child = new Program(); A p = new A(); p.x = 10; child.z = 30; p.setvalue(20,child.z); Console.WriteLine(p.sum()); Console.ReadKey(); 1/12/

13 Accessing Modifiers or Accessibility Levels. 4. Internal Access Specifier: The internal access specifier hides its member variables and methods from other classes and objects, that is resides in other namespace. The variable or classes that are declared with internal can be access by any member within application. It is the default access specifiers for a class in C# programming. using System; namespace InternalAcess class A internal string name; public void print() Console.WriteLine(name); class Program static void Main(string[] args) A n=new A(); n.name="amar"; n.print(); 1/12/

14 Thanks Any Questions 1/12/

Duhok Polytechnic University Amedi Technical Institute/ IT Dept. Halkawt Rajab Hussain

Duhok Polytechnic University Amedi Technical Institute/ IT Dept. By Halkawt Rajab Hussain 2016-04-02 Inheritance: Concept of Inheritance. Types of inheritance. Virtual base class method. Interface. 4/1/2017