AutoCompleteTextBox in C# Windows Form Application

In this Article, We will learn how to create AutoCompleteTextBox using C# Windows Form Application. In my previous article, we learned How to Search Records in DataGridView Using C#.

Let's Begin.
Create a new Windows Form Application.

Drop a Label and TextBox Control from the ToolBox.

Now go to Code behind file(.cs code) and add the following Code:

using System; using System.Windows.Forms; namespace AutoCompleteTextBoxDemo {     public partial class Form1 : Form     {         public Form1()         {             InitializeComponent();         }         //AutoCompleteData Method         private void autoCompleteData()         {             //Set AutoCompleteSource property of txt_StateName as CustomSource             txt_StateName.AutoCompleteSource = AutoCompleteSource.CustomSource;             //Set AutoCompleteMode property of txt_StateName as SuggestAppend. SuggestAppend Applies both Suggest and Append             txt_StateName.AutoCompleteMode = AutoCompleteMode.SuggestAppend;             txt_StateName.AutoCompleteCustomSource.AddRange(new string[]{"Maharastra","Andhra Pradesh","Assam","Punjab","Arunachal Pradesh","Bihar","Goa","Gujarat","Haryana"});         }         private void Form1_Load(object sender, EventArgs e)         {             autoCompleteData();         }     } }

In the preeceding code, We set the AutoCompleteSource, AutoCompleteMode and AutoCompleteCustomSource properties of Textbox named as txt_StateName so that it automatically completes the input string.
Preview:

AutoComplete TextBox using a Database:
In this example, We will Suggest/Append the data in TextBox(txt_StateName) from the Database. For Demonstration, I have created a Database (named Sample). Add a Table, tbl_State. The following is the table schema for creating tbl_State.

Add the following lines of code:

using System; using System.Windows.Forms; using System.Data.SqlClient; namespace AutoCompleteTextBoxDemo {     public partial class Form2 : Form     {         public Form2()         {             InitializeComponent();         }         private void autoCompleteData()         {             SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Sample;Integrated Security=true;");             SqlCommand com = new SqlCommand("Select State from tbl_State", con);             con.Open();             SqlDataReader rdr = com.ExecuteReader();             //AutoCompleteStringCollection Contains a collection of strings to use for the auto-complete feature on certain Windows Forms controls.             AutoCompleteStringCollection autoCompleteCollection = new AutoCompleteStringCollection();             while (rdr.Read())             {                 autoCompleteCollection.Add(rdr.GetString(0));             }             //Set AutoCompleteSource property of txt_StateName as CustomSource             txt_StateName.AutoCompleteSource = AutoCompleteSource.CustomSource;             //Set AutoCompleteMode property of txt_StateName as SuggestAppend. SuggestAppend Applies both Suggest and Append             txt_StateName.AutoCompleteMode = AutoCompleteMode.SuggestAppend;             txt_StateName.AutoCompleteCustomSource = autoCompleteCollection;             con.Close();         }         //Form2_Load Event         private void Form2_Load(object sender, EventArgs e)         {             autoCompleteData();         }     } }

Preview:

Hope you like it. Thanks.

[Download Source Code via Google Drive]