Control for Find text in RichTextBox C#

Question

Hi, I created a notepad in C#. I added a button named "Search this Rich Text Box". Now I want to implement the code for the search button that search and highlight the text in the rich textbox. Please give the code for that.

Answer 1

Hello,

This will start the search again automatically:

private int Start = -1;
        private void FindText()
        {
            int Index = richTextBox1.Text.IndexOf(txtSearchWord.Text, Start + 1, StringComparison.OrdinalIgnoreCase);

            if (richTextBox1.Text.ToUpper().Contains(txtSearchWord.Text.ToUpper()))
            {
                if (Index != -1)
                {
                    richTextBox1.Focus();
                    richTextBox1.SelectionStart = Index;
                    richTextBox1.SelectionLength = txtSearchWord.Text.Length;
                    richTextBox1.ScrollToCaret();
                    Start = Index;
                }
                else
                {
                    Start = -1;
                    Index = richTextBox1.Text.IndexOf(txtSearchWord.Text, Start + 1, StringComparison.OrdinalIgnoreCase);
                    richTextBox1.Focus();
                    richTextBox1.SelectionStart = Index;
                    richTextBox1.SelectionLength = txtSearchWord.Text.Length;
                    richTextBox1.ScrollToCaret();
                    Start = Index;
                }
            }
            else
            {
                MessageBox.Show("The following text [" + txtSearchWord.Text + "] was not found.");
            }
        }

I hope it helps.

Answer 2

Hello,

You can try this code:

private int Start = -1;

        private void FindText()
        {
            int Index = richTextBox1.Text.IndexOf(txtSearchWord.Text, Start + 1, StringComparison.OrdinalIgnoreCase);

            if (richTextBox1.Text.ToUpper().Contains(txtSearchWord.Text.ToUpper()))
            {
                if (Index != -1)
                {
                    richTextBox1.Focus();
                    richTextBox1.SelectionStart = Index;
                    richTextBox1.SelectionLength = txtSearchWord.Text.Length;
                    richTextBox1.ScrollToCaret();
                    Start = Index;
                }
                else
                {
                    MessageBox.Show("Found all the instances of [" + txtSearchWord.Text + "]", "End Search");
                    Start = -1;
                }
            }
            else
            {
                MessageBox.Show("The following text [" + txtSearchWord.Text + "] was not found.");
            }
        }

This code assumes that the RichtextBox is named: richTextBox1 and the Search Textbox is named: txtSearchWord. To change the search to non-case sensitive, change this line:

int Index = richTextBox1.Text.IndexOf(txtSearchWord .Text, Start + 1, StringComparison.Ordinal);

To:

int Index = richTextBox1.Text.IndexOf(txtSearchWord .Text, Start + 1, StringComparison.OrdinalIgnoreCase);

I hope it helps.

Answer 3

Hi HemanthB-9452,
You can use RichTextBox.Find method to searche for text within the contents of the RichTextBox.
Here is my test code you can rfer to.

private void Form1_Load(object sender, EventArgs e)  
{  
    richTextBox1.Text = "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.";  
}  
  
private void Search_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 Clear_Click(object sender, EventArgs e)  
{  
    richTextBox1.SelectionStart = 0;  
    richTextBox1.SelectAll();  
    richTextBox1.SelectionBackColor = Color.White;  
}  

The result:

Best Regards,
Daniel Zhang

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