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

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 2

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 3

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 4

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;
    }

Answer 5

    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 6

I would do it like that because all the other answers highlight the text, but doesnt change it back after you searched again.

Use the RichText Find Method to find the starting index for the searching word.

public int FindMyText(string searchText, int searchStart, int searchEnd)
    {
        int returnValue = -1;

        if (searchText.Length > 0 && searchStart >= 0)
        {
            if (searchEnd > searchStart || searchEnd == -1)
            {
                int indexToText = richTextBox1.Find(searchText, searchStart, searchEnd, RichTextBoxFinds.MatchCase);
                if (indexToText >= 0)
                {
                    returnValue = indexToText;
                }
            }
        }

        return returnValue;
    }

Use a Button or TextChangeListener and Search for your word.

private void button1_Click(object sender, EventArgs e)
{
        // Select the first char in your Richtextbox
        richTextBox1.SelectionStart = 0;

        richTextBox1.SelectionLength = richTextBox1.TextLength;
        // Select until the end
        richTextBox1.SelectionColor = Color.Black;
        // Make the Text Color black

        //Use an Inputfield to add the searching word
        var word = txtSearch.Text;
        //verify the minimum length otherwise it may freeze if you dont have text inside
        if (word.Length > 3)
        {
          int s_start = richTextBox1.SelectionStart, startIndex = 0, index;
          while ((index = FindMyText(word, startIndex, richTextBox1.TextLength)) != -1)
            {
            // goes through all possible found words and color them blue (starting index to end)
                richTextBox1.Select(index, word.Length);
                richTextBox1.SelectionColor = Color.Blue;
                startIndex = index + word.Length;
            }
            // Color everything between in color black to highlight only found words       
            richTextBox1.SelectionStart = startIndex;
            richTextBox1.SelectionLength = 0;
            richTextBox1.SelectionColor = Color.Black;
        }
}

I would highly recommend to set a minimum word length to avoid freezing and high memory allocation.