Highlight all searched words

Question

In my RichtextBox, if I have written as below.

This is my pen,
his pen is beautiful.

Now I search word "is" then output would be as below.

All "is" should be highlighted.

Answer 1

Using this method, you will able to highlight multiple words at the same time. Or you can easily skip the foreach part and use it to highlight just a single word.

private void HighlightWords(string[] words)
{
    foreach (string word in words)
    {
        int startIndex = 0;
        while (startIndex < rich.TextLength)
        {

            int wordStartIndex = rich.Find(word, startIndex, RichTextBoxFinds.None);
            if (wordStartIndex != -1)
            {
                rich.SelectionStart = wordStartIndex;
                rich.SelectionLength = word.Length;
                rich.SelectionBackColor = Color.Yellow;
            }
            else
                break;
            startIndex += wordStartIndex + word.Length;
        }
    }
}

Answer 2

What about:

static class Utility {
    public static void HighlightText(this RichTextBox myRtb, string word, Color color) {  

       if (word == string.Empty)
            return;

       int s_start = myRtb.SelectionStart, startIndex = 0, index;

       while((index = myRtb.Text.IndexOf(word, startIndex)) != -1) {
           myRtb.Select(index, word.Length);
           myRtb.SelectionColor = color;

           startIndex = index + word.Length;
       }

       myRtb.SelectionStart = s_start;
       myRtb.SelectionLength = 0;
       myRtb.SelectionColor = Color.Black;
    }
}

Answer 3

    private void button3_Click(object sender, EventArgs e)
    {
        if (textBox1.Text != "")
        {
            for (int i = 0; i < richTextBox1.TextLength; i++)
            {
                richTextBox1.Find(textBox1.Text, i, RichTextBoxFinds.None);
                richTextBox1.SelectionBackColor = Color.Red;
            }
        }
        else
        {
            for (int i = 0; i < richTextBox1.TextLength; i++)
            {
                richTextBox1.SelectAll();
                richTextBox1.SelectionBackColor = Color.White;
            }
        }
    }[lets make it!][1]

Answer 4

This will show all the searched criteria at the same time.

Using: 1 Textbox (to enter the text to search for) and 1 Button (to Run the Search).

Enter your search criteria inside the textbox and press search button.

        // On Search Button Click: RichTextBox ("rtb") will display all the words inside the document
    private void btn_Search_Click(object sender, EventArgs e)
    {
        try
        {
            if (rtb.Text != string.Empty)
            {// if the ritchtextbox is not empty; highlight the search criteria
                int index = 0;
                String temp = rtb.Text;
                rtb.Text = "";
                rtb.Text = temp;
                while (index < rtb.Text.LastIndexOf(txt_Search.Text))
                {
                    rtb.Find(txt_Search.Text, index, rtb.TextLength, RichTextBoxFinds.None);
                    rtb.SelectionBackColor = Color.Yellow;
                    index = rtb.Text.IndexOf(txt_Search.Text, index) + 1;
                    rtb.Select();
                }
            }
        }

        catch (Exception ex) { MessageBox.Show(ex.Message, "Error"); }
    }
}

}

Answer 5

Looks like this would do it.

http://www.dotnetcurry.com/ShowArticle.aspx?ID=146

int start = 0;
int indexOfSearchText = 0;

    private void btnFind_Click(object sender, EventArgs e)
    {
        int startindex = 0;

        if(txtSearch.Text.Length > 0)
            startindex = FindMyText(txtSearch.Text.Trim(), start, rtb.Text.Length);

        // If string was found in the RichTextBox, highlight it
        if (startindex >= 0)
        {
            // Set the highlight color as red
            rtb.SelectionColor = Color.Red;
            // Find the end index. End Index = number of characters in textbox
            int endindex = txtSearch.Text.Length;
            // Highlight the search string
            rtb.Select(startindex, endindex);
            // mark the start position after the position of
            // last search string
            start = startindex + endindex;
        }
    }

    public int FindMyText(string txtToSearch, int searchStart, int searchEnd)
    {
        // Unselect the previously searched string
        if (searchStart > 0 && searchEnd > 0 && indexOfSearchText >= 0)
        {
            rtb.Undo();
        }

        // Set the return value to -1 by default.
        int retVal = -1;

        // A valid starting index should be specified.
        // if indexOfSearchText = -1, the end of search
        if (searchStart >= 0 && indexOfSearchText >=0)
        {
            // A valid ending index
            if (searchEnd > searchStart || searchEnd == -1)
            {
                // Find the position of search string in RichTextBox
                indexOfSearchText = rtb.Find(txtToSearch, searchStart, searchEnd, RichTextBoxFinds.None);
                // Determine whether the text was found in richTextBox1.
                if (indexOfSearchText != -1)
                {
                    // Return the index to the specified search text.
                    retVal = indexOfSearchText;
                }
            }
        }
        return retVal;
    }

// Reset the richtextbox when user changes the search string
    private void textBox1_TextChanged(object sender, EventArgs e)
    {
        start = 0;
        indexOfSearchText = 0;
    }

Answer 6

If you only want to match the whole word you can use this, note that this ignores case and also the |s\b means that plurals get highlighted e.g. Cat matches cats but not caterpiller :

    public static void HighlightText(RichTextBox myRtb, string word, Color color)
    {
        if (word == string.Empty)
            return;
        var reg = new Regex(@"\b" + word + @"(\b|s\b)",RegexOptions.IgnoreCase);

        foreach (Match match in reg.Matches(myRtb.Text))
        {
            myRtb.Select(match.Index, match.Length);
            myRtb.SelectionColor = color;
        }

        myRtb.SelectionLength = 0;
        myRtb.SelectionColor = Color.Black;
    }