Csharp/CSharp Tutorial/Class/static Class

Demonstrate a static class.

<source lang="csharp">using System;

static class MathFunction {

 // Return the reciprocal of a value. 
 static public double reciprocal(double num) { 
   return 1/num; 
 } 

 // Return the fractional part of a value. 
 static public double fracPart(double num) { 
   return num - (int) num; 
 } 

 // Return true if num is even. 
 static public bool isEven(double num) { 
   return (num % 2) == 0 ? true : false; 
 } 

 // Return true of num is odd. 
 static public bool isOdd(double num) { 
   return !isEven(num); 
 } 

}

class MainClass {

 public static void Main() {    
   Console.WriteLine("Reciprocal of 5 is " + 
                     MathFunction.reciprocal(5.0)); 

   Console.WriteLine("Fractional part of 4.234 is " + 
                     MathFunction.fracPart(4.234)); 

   if(MathFunction.isEven(10)) 
     Console.WriteLine("10 is even."); 

   if(MathFunction.isOdd(5)) 
     Console.WriteLine("5 is odd."); 

   // The following attempt to create an instance of  
   // MathFunction will cause an error. 

// MathFunction ob = new MathFunction(); // Wrong!

 }  

}</source>

Reciprocal of 5 is 0.2
Fractional part of 4.234 is 0.234
10 is even.
5 is odd.

Static class and its inner class

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

   public static void DoWork() {
       ++CallCount;
       Console.WriteLine( "StaticClass.DoWork()" );
   }
   public class NestedClass {
       public NestedClass() {
           Console.WriteLine( "NestedClass.NestedClass()" );
       }
   }
   public static long CallCount = 0;

} public static class MainClass {

   static void Main() {
       StaticClass.DoWork();
       StaticClass.NestedClass nested = new StaticClass.NestedClass();
       Console.WriteLine( "CallCount = {0}", StaticClass.CallCount );
   }

}</source>

StaticClass.DoWork()
NestedClass.NestedClass()
CallCount = 1

Static inner class constructor

<source lang="csharp">using System; using System.ruponentModel;

       class Outer<T>
       {
           public class Inner<U, V>
           {
               static Inner()
               {
                   Console.WriteLine("Outer<{0}>.Inner<{1},{2}>",
                                     typeof(T).Name,
                                     typeof(U).Name,
                                     typeof(V).Name);
               }
               public static void DummyMethod()
               {
               }
           }
           static void Main()
           {
               Outer<int>.Inner<string, DateTime>.DummyMethod();
           }
       }</source>