Search And Highlight Text In Rich TextBox

Menaka Priyadharshini B

C#Windows Forms Visual Studio 2017Search and Highlight Text

13 Comments

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Tuan Nguyen Anh6y ago
At this line, startindex += wordstartIndex + word.Length; you should change to startindex = wordstartIndex + word.Length; because wordstartIndex + word.Length is already contains the next postion to lookup
LONE WOLF7y ago
Why when i execute it crashes ? Anyone can help ?
- Menaka Priyadharshini B7y ago
  Can you explain in detail
- Micah Parker7y ago
  I believe you are putting it in the wrong click event ...
- Micah Parker7y ago
  - Also, it is rude not to respond to Menakapriyadharshini Baskarpillai, after she nicely replied and tried to help.
Yılmaz Kara7y ago
A very useful article, thank you. For those who want to see a different use, I found an article like this: http://www.ozcandegirmenci.com/searchable-richtextbox-control/ can review friends who are in need. In addition, you can access the project via github. Thanks Meneka.
- Menaka Priyadharshini B7y ago
  Thank you lot
Archit Shrivastava8y ago
Nice article
maha lakshmi8y ago
Nice article
- Menaka Priyadharshini B8y ago
  Thank you ..
maha lakshmi8y ago
Good article
Guest User8y ago
Good article
- Menaka Priyadharshini B8y ago
  Thank you sis

Introduction

In this article, I am going to explain how to search and highlight text in Rich TextBox in a Windows Forms app using Visual Studio 2017.

STEP 1 - Start the Project

Let's create a new project using Visual Studio 2017.

Select New Project--->Visual C#-->Windows Forms App (.NET Framework), give your project a name and click OK.

This action creates a WinForms project with a default form and you should see the Windows designer.

STEP 2 - Drag and Drop Control

Let's add a control to the form by dragging it from Toolbox and dropping it to the form. You will see a Rich TextBox 1 is added to the form. This control is now available to you in the code behind.

Search and Highlight Text

The textbox will be used to enter the search string and on the button click, we will be performing a search in the Rich TextBox. Add a class variable called 'start'. This variable will be the start position within the control text from where you need to begin searching.

Also, add another variable called 'IndexofsearchText' to hold position/index of the search string in the Rich TextBox. RTF stands for Rich Text Format, and this describes a certain file type where text formatting is encoded with special character embedded in the text. Programs such as Microsoft Word can use RTF documents.

Now, let's add another control to the form by dragging the other control from Toolbox to the form. You may also want to change the properties of the other controls.

Change the text of button and label control to what you like.

STEP 3 - Coding

Follow the coding given below,

public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string[] words = textBox1.Text.Split(',');
foreach(string word in words)
{
int startindex = 0;
while(startindex < richTextBox1.TextLength)
{
int wordstartIndex = richTextBox1.Find(word, startindex, RichTextBoxFinds.None);
if (wordstartIndex != -1)
{
richTextBox1.SelectionStart = wordstartIndex;
richTextBox1.SelectionLength = word.Length;
richTextBox1.SelectionBackColor = Color.Yellow;
}
else
break;
startindex += wordstartIndex + word.Length;
}
}
}
private void button2_Click(object sender, EventArgs e)
{
richTextBox1.SelectionStart = 0;
richTextBox1.SelectAll();
richTextBox1.SelectionBackColor = Color.White;
}
}

STEP 4 - Compile and Run

Now, simply compile and run the aplication.

Copy and paste the paragraph in Rich TextBox. Enter the text in the Textbox you need to search and highlight in the paragraph. After clicking the search Button, the Text entered in the Textbox will be searched and highlighted in the paragraph.

Summary

In this basic article, you saw how to search and highlight text in Rich TextBox control. Hope you found this article interesting. For any feedback, please post it as a comment at the bottom of this article. Thank you!