List in c#

In this blog we see how to use a List in c#.

The class List is new in dot net frame work 2 .0, it belongs to the spaceName System.Collections.Generic , it is a collection of objects (Image,int,string ...) accessed by an index , the number of its elements is not fixed you can add and remove any time you want at run time; So it is  very useful and so easy to manipulate and that's what I am going to show you :

Code Behind the form:

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

 

namespace Lists

{

    public partial class Form1 : Form

    {

 

        List<string> countries = new List<string>(); // instance of a string list

 

        public void ListBoxrefresh()

        {  // method refreshing the list box when

            //we delete or add an item to our countries list

            listBox1.DataSource = null;

            listBox1.DataSource = countries; // we use "countries" as a datasource to fill the listBox

            label1.Text = countries.Count.ToString();

        }

 

        public Form1()

        {

            InitializeComponent();

        }

 

        private void Form1_Load(object sender, EventArgs e)

        {

 

            countries.Add("ANDORRA"); // add elemnts to our "countries" list

            countries.Add("AUSTRIA");

            countries.Add("BELGIUM");

            countries.Add("BELARUS");

            countries.Add("BULGARIA");

            countries.Add("CROATIA");

            countries.Add("CYPRUS");

            countries.Add("DENMARK");

            countries.Add("ESTONIA");

            countries.Add("FINLAND");

            countries.Add("FRANCE");

            countries.Add("GERMANY");

 

            listBox1.DataSource = countries; // make "countries" as DataSource of the list box

            label1.Text = countries.Count.ToString();      // get the number of "countries" items

 

        }

        private void button1_Click(object sender, EventArgs e)

        {

            if (!string.IsNullOrWhiteSpace(textBox1.Text))

            {

                countries.Add(textBox1.Text.ToUpper());// add element from the textBox

                ListBoxrefresh();

 

 

            }

        }

 

        private void button2_Click(object sender, EventArgs e)

        {

            if (listBox1.SelectedIndex != -1)

            {

                countries.RemoveAt(listBox1.SelectedIndex);// remove an element from "countries"

                //by specifying it's index retreived from the lisTbox

                ListBoxrefresh();

            }

        }

    }

}

 
 
The UI

Let's resume:

1. We created a list of string :
   
   List<string> countries =new List<string>();
    
2. We added items :
   
   countries.Add("ANDORRA");
   countries.Add("AUSTRIA");
    
3. We used Listbox to display items of countries list
4. We add an elements by :
   
    countries.Add(textBox1.Text.ToUpper());
    
5. We remove an elements by :
   
   countries.RemoveAt(listBox1.SelectedIndex);