ch1_09.cs

《c#技术内幕代码》

using System;
using System.Collections;

class CH1_9 {

   public static void Main() 
   {
	// Create a hashtable with a default comparison operator
	// and initially 10 elements.
	
	Hashtable ht = new Hashtable(10);
	
	// Add ten strings to the hashtable associated with a
	// key value (integer).
	
	ht.Add( 100, "Science");
	ht.Add( 200, "Math");
	ht.Add( 300, "English");
	ht.Add( 400, "History");
	ht.Add( 500, "Gym");
	
	// How many elements does the table contain?
	Console.WriteLine("The hashtable contains {0} elements", ht.Count);
	
	// Does it contain the entry for Gym? How about Recess?
	Console.WriteLine("The hashtable contains 500? {0}", ht.Contains(500));
	Console.WriteLine("The hashtable contains 600? {0}", ht.Contains(600));
	
	// What is the value for 400? 800?
	Console.WriteLine("The value for 400 is {0}", ht[400]);
	Console.WriteLine("The value for 800 is {0}", ht[800]);
	
	// See if the values are null
	if ( ht[400] == null )
	   Console.WriteLine( "Entry 400 is null" );
	else
	   Console.WriteLine( "Entry 400 is NOT null" );
	   
	if ( ht[800] == null )
	   Console.WriteLine( "Entry 800 is null" );
	else
	   Console.WriteLine( "Entry 800 is NOT null" );

   }
}