Csharp/CSharp Tutorial/Class/Method Return

How to define methods that return a value and accept parameters

<source lang="csharp">class Car {

 public int yearBuilt;
 public double maximumSpeed;
 public int Age(int currentYear)
 {
   int age = currentYear - yearBuilt;
   return age;
 }
 public double Distance(double initialSpeed, double time)
 {
   return (initialSpeed + maximumSpeed) / 2 * time;
 }

} class MainClass {

 public static void Main()
 {
   Car myCar = new Car();
   myCar.yearBuilt = 2000;
   myCar.maximumSpeed = 150;
   int age = myCar.Age(2001);
   System.Console.WriteLine("myCar is " + age + " year old.");
   System.Console.WriteLine("myCar travels " + myCar.Distance(31, .25) + " miles.");
 }

}</source>

myCar is 1 year old.
myCar travels 22.625 miles.

Methods That Return a Value and Accept Parameters

<source lang="csharp">public class Product {

   public int yearBuilt;
   public double maximumSpeed;
   public int Age(int currentYear) {
       int age = currentYear - yearBuilt;
       return age;
   }
   public double Distance(double initialSpeed, double time) {
       return (initialSpeed + maximumSpeed) / 2 * time;
   }

}

class MainClass{

   public static void Main() {
       Product redPorsche = new Product();
       redPorsche.yearBuilt = 2000;
       redPorsche.maximumSpeed = 150;
       int age = redPorsche.Age(2001);
       System.Console.WriteLine("redPorsche is " + age + " year old.");
       System.Console.WriteLine("redPorsche travels " + redPorsche.Distance(31, .25) + " miles.");
   }

}</source>

Return an array

<source lang="csharp">using System;

class Factor {

 public int[] findfactors(int num, out int numfactors) { 
   int[] facts = new int[80]; 
   int i, j; 

   for(i=2, j=0; i < num/2 + 1; i++)  
     if( (num%i)==0 ) { 
       facts[j] = i; 
       j++; 
     } 
    
   numfactors = j; 
   return facts; 
 } 

}

class MainClass {

 public static void Main() {   
   Factor f = new Factor(); 
   int numfactors; 
   int[] factors; 

   factors = f.findfactors(1000, out numfactors); 

   Console.WriteLine("Factors for 1000 are: "); 
   for(int i=0; i < numfactors; i++) 
     Console.Write(factors[i] + " "); 
      
   Console.WriteLine();    
 } 

}</source>

Factors for 1000 are:
2 4 5 8 10 20 25 40 50 100 125 200 250 500

Return an object

<source lang="csharp">using System;

class Rect {

 int width; 
 int height; 

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

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

 public void show() { 
   Console.WriteLine(width + " " + height); 
 } 

 public Rect enlarge(int factor) { 
   return new Rect(width * factor, height * factor); 
 } 

}

class MainClass {

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

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

   Console.WriteLine(); 

   // create a rectangle that is twice as big as r1 
   Rect r2 = r1.enlarge(2); 

   Console.Write("Dimensions of r2: "); 
   r2.show(); 
   Console.WriteLine("Area of r2 " + r2.area()); 
 } 

}</source>

Dimensions of r1: 4 5
Area of r1: 20
Dimensions of r2: 8 10
Area of r2 80

Return int from function

Methods return a value to the calling routine using this form of return:

<source lang="csharp">return value;</source>

Use a class factory

<source lang="csharp">using System;

class MyClass {

 int a, b; // private 

 // Create a class factory for MyClass. 
 public MyClass factory(int i, int j) { 
   MyClass t = new MyClass(); 
   
   t.a = i; 
   t.b = j; 

   return t; // return an object 
 } 

 public void show() { 
   Console.WriteLine("a and b: " + a + " " + b); 
 } 

}

class MakeObjects {

 public static void Main() {   
   MyClass ob = new MyClass(); 
   int i, j; 

   // generate objects using the factory 
   for(i=0, j=10; i < 10; i++, j--) { 
     MyClass anotherOb = ob.factory(i, j); // make an object 
     anotherOb.show(); 
   } 
      
   Console.WriteLine();    
 } 

}</source>

a and b: 0 10
a and b: 1 9
a and b: 2 8
a and b: 3 7
a and b: 4 6
a and b: 5 5
a and b: 6 4
a and b: 7 3
a and b: 8 2
a and b: 9 1