C# Collection Tutorial-Part-1

CSharp Collections are data structures that holds data in different ways for flexible operations . C# Collection classes are defined as part of the System.Collections or System.Collections.Generic namespace.

Most collection classes implement the same interfaces, and these interfaces may be inherited to create new collection classes that fit more specialized data storage needs. The following tutorial shows how to implement collection classes in C# programming.

ArrayList is one of the most flexible data structure from CSharp Collections. ArrayList contains a simple list of values. ArrayList implements the IList interface using an array and very easily we can add , insert , delete , view etc. It is very flexible because we can add without any size information , that is it will grow dynamically and also shrink .

  Add : Add an Item in an ArrayList
  Insert : Insert an Item in a specified position in an ArrayList
  Remove : Remove an Item from ArrayList
  RemoveAt: remove an item from a specified position

  Sort : Sort Items in an ArrayList

How to add an Item in an ArrayList ?

  Syntax : ArrayList.add(object)
  object : The Item to be add the ArrayList
  ArrayList arr;

  arr.Add("Item1");

How to Insert an Item in an ArrayList ?

  Syntax : ArrayList.insert(index,object)
  index : The position of the item in an ArrayList
  object : The Item to be add the ArrayList
  ArrayList arr;

  arr.Insert(3, "Item3");

How to remove an item from arrayList ?

  Syntax : ArrayList.Remove(object)
  object : The Item to be add the ArrayList

  arr.Remove("item2")

How to remove an item in a specified position from an ArrayList ?

  Syntax : ArrayList.RemoveAt(index)
  index : the position of an item to remove from an ArrayList

  ItemList.RemoveAt(2)

How to sort ArrayList ?

  Syntax : ArrayList.Sort()

The following CSharp source code shows some function in ArrayList

using System;
using System.Collections;
using System.Windows.Forms;

namespace WindowsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int i = 0;
            ArrayList ItemList = new ArrayList();
            ItemList.Add("Item4");
            ItemList.Add("Item5");
            ItemList.Add("Item2");
            ItemList.Add("Item1");
            ItemList.Add("Item3");
            MessageBox.Show ("Shows Added Items");
            for (i = 0; i < = ItemList.Count - 1; i++)
            {
                MessageBox.Show(ItemList[i].ToString());
            }
            //insert an item 
            ItemList.Insert(3, "Item6");
            //sort itemms in an arraylist 
            ItemList.Sort();
            //remove an item 
            ItemList.Remove("Item1");
            //remove item from a specified index 
            ItemList.RemoveAt(3);
            MessageBox.Show("Shows final Items the ArrayList");
            for (i = 0; i < = ItemList.Count - 1; i++)
            {
                MessageBox.Show(ItemList[i].ToString());
            }
        }
    }
}

When you execute this C# program , at first add five items in the arraylist and displays. Then again one more item inserted in the third position , and then sort all items. Next it remove the item1 and also remove the item in the third position . Finally it shows the existing items.