Csharp/CSharp Tutorial/Class/Member Method

Define methods

1. Methods are subroutines that manipulate the data defined by the class and provide access to that data.
2. Other parts of your program will interact with a class through its methods.
3. The general form of a method is shown here:

<source lang="csharp">access ret-type name(parameter-list) {

   // body of method

}</source>

Define Rectangle class with method to compute the area

<source lang="csharp">using System;

class Rect {

 public int width; 
 public int height; 

 public Rect(int w, int h) { 
   width = w; 
   height = h; 
 } 

 public int area() { 
   return width * height; 
 } 

}

class UseRect {

 public static void Main() {   
   Rect r1 = new Rect(4, 5); 
   Rect r2 = new Rect(7, 9); 

   Console.WriteLine("Area of r1: " + r1.area()); 

   Console.WriteLine("Area of r2: " + r2.area()); 

 } 

}</source>

Area of r1: 20
Area of r2: 63

Member Functions

<source lang="csharp">using System; class Point {

   public Point(int x, int y)
   {
       this.x = x;
       this.y = y;
   }
   
   // accessor functions
   public int GetX() {
       return(x);
   }
   public int GetY() {
       return(y);
   }
   
   // variables now private
   int x;
   int y;

} class MainClass {

   public static void Main()
   {
       Point myPoint = new Point(10, 15);
       Console.WriteLine("myPoint.X {0}", myPoint.GetX());
       Console.WriteLine("myPoint.Y {0}", myPoint.GetY());
   }

}</source>

myPoint.X 10
myPoint.Y 15

Nested methods

<source lang="csharp">using System; class MainClass {

  static void MethodA(int par1, int par2)
  {
     Console.WriteLine("Enter MethodA: {0}, {1}", par1, par2);
     MethodB(11, 18);
     Console.WriteLine("Exit MethodA");
  }
  static void MethodB(int par1, int par2)
  {
     Console.WriteLine("Enter MethodB: {0}, {1}", par1, par2);
     Console.WriteLine("Exit MethodB");
  }
  static void Main()
  {
     MethodA(15, 30);
  }

}</source>

Enter MethodA: 15, 30
Enter MethodB: 11, 18
Exit MethodB
Exit MethodA

Object Class Methods

<source lang="csharp">using System; public class Product {

   public string make;
   public string model;
   public Product(string make, string model) {
       this.make = make;
       this.model = model;
   }
   public void Display() {
       Console.WriteLine("make = " + make);
       Console.WriteLine("model = " + model);
   }
   public static Product Copy(Product p) {
       return (Product)p.MemberwiseClone();
   }

} class MainClass {

   public static void Main() {
       Console.WriteLine("Creating Product objects");
       Product myProduct = new Product("Toyota", "MR2");
       Product myOtherProduct = new Product("Porsche", "Boxter");
       myProduct.Display();
       myOtherProduct.Display();
       Console.WriteLine("myProduct.ToString() = " + myProduct.ToString());
       Console.WriteLine("myProduct.GetType() = " + myProduct.GetType());
       Console.WriteLine("myProduct.GetHashCode() = " + myProduct.GetHashCode());
       Console.WriteLine("Product.Equals(myProduct, myOtherProduct) = " + Product.Equals(myProduct, myOtherProduct));
       Console.WriteLine("Product.ReferenceEquals(myProduct, myOtherProduct) = " + Product.ReferenceEquals(myProduct, myOtherProduct));
       myProduct = myOtherProduct;
       Console.WriteLine("Product.Equals(myProduct, myOtherProduct) = " + Product.Equals(myProduct, myOtherProduct));
       Console.WriteLine("Product.ReferenceEquals(myProduct, myOtherProduct) = " + Product.ReferenceEquals(myProduct, myOtherProduct));
       Product myOldProduct = Product.Copy(myProduct);
       myOldProduct.Display();
   }

}</source>

Return a value from a member method

<source lang="csharp">using System;

class Building {

 public int area;      
 public int occupants; 

 // Return the area per person.  
 public int areaPerPerson() {  
   return area / occupants; 
 }  

}

class MainClass {

 public static void Main() {   
   Building house = new Building();   
   Building office = new Building(); 
   int areaPP; // area per person 

   house.occupants = 4;  
   house.area = 2500;  

   office.occupants = 25;  
   office.area = 4200;  
  
   areaPP = house.areaPerPerson(); 

   Console.WriteLine("house has:\n  " + 
                     house.occupants + " occupants\n  " + 
                     house.area + " total area\n  " + 
                     areaPP + " area per person"); 


   Console.WriteLine(); 

   // obtain area per person for office 
   areaPP = office.areaPerPerson(); 

   Console.WriteLine("office has:\n  " + 
                     office.occupants + " occupants\n  " + 
                     office.area + " total area\n  " + 
                     areaPP + " area per person"); 
 }   

}</source>

house has:
  4 occupants
  2500 total area
  625 area per person
office has:
  25 occupants
  4200 total area
  168 area per person