ArrayList

Hi Dino,

As luck would have it, Mahesh Chand has just written a free book for C# beginners which can be downloaded here:

http://www.c-sharpcorner.com/UploadFile/mahesh/csp08202007084545AM/csp.aspx 

Other good online resources to check out include the following (the second one's best if you already know a bit of C/C++):

http://www.publicjoe.co.uk/csharp/csharp.html  

http://www.charlespetzold.com/dotnet/

Thx Alan.  Do you have any idea where i can find a good C# book to study? any specific C# book?

Many thx

/Dino

Here's a possible approach which still works if the ArrayList contains elements of different types:

using System;
using System.Collections;

class Program
{
    static void Main()
    {
       ArrayList al = new ArrayList();
       al.Add(123);
       al.Add("hello");
       al.Add(456.78);
       al.Add("hello");
       al.Add(456.78);
       al.Add(true);
       al.Add(new MyClass());
       al.Add(new MyClass()); // different obect, so not duplicated
       MyClass mc = new MyClass();
       al.Add(mc);
       al.Add(mc); //same object, so duplicated
       bool containsDuplicates = false;

       for (int i = 0; i < al.Count - 1; i++)
       {
         if (al.IndexOf(al[i], i + 1) > -1)
         {
            Console.WriteLine("{0} is duplicated", al[i]);
            if (!containsDuplicates) containsDuplicates = true;
         }
       }

       if (!containsDuplicates)
          Console.WriteLine("There are no duplicated objects");       
       Console.ReadLine();
    }
}

class MyClass
{
   static int lastId;

   public readonly int Id;

   public MyClass()
   {
     Id = ++lastId;
   }

   public override string ToString()
   {
      return "MyClass object #" + Id.ToString();
   }     
}