HOWTO: Find and Highlight Text in the RichTextBox Control

• Professional and Enterprise Editions of Microsoft Visual Basic, 32-bit only, for Windows, version 4.0

SUMMARY

In many applications there is a function to search and highlight keywords in a text window. The RichTextBox control in Visual Basic 4.0 can be made to provide this functionality, as shown in the sample code below.

MORE INFORMATION

1. Start a new project in Visual Basic. Form1 is created by default.

2. Place a Command button and a RichTextBox on Form1. Set the Text property of the RichTextBox to "This is an example of finding text in a rich text box."

3. Add the following code to the General Declarations section of Form1:

   Option Explicit

      Private Sub Command1_Click()
        HighlightWords RichTextBox1, "text", vbRed
      End Sub
   
      Private Function HighlightWords(rtb As RichTextBox, _
                                  sFindString As String, _
                                  lColor As Long) _
                                  As Integer
   
        Dim lFoundPos As Long           'Position of first character of match
        Dim lFindLength As Long         'Length of string to find
        Dim lOriginalSelStart As Long
        Dim lOriginalSelLength As Long
        Dim iMatchCount As Integer      'Number of matches
   
        'Save the insertion points current location and length
        lOriginalSelStart = rtb.SelStart
        lOriginalSelLength = rtb.SelLength
   
        'Cache the length of the string to find
        lFindLength = Len(sFindString)
   
        'Attempt to find the first match
        lFoundPos = rtb.Find(sFindString, 0, , rtfNoHighlight)
        While lFoundPos > 0
          iMatchCount = iMatchCount + 1
   
          rtb.SelStart = lFoundPos
          'The SelLength property is set to 0 as
          'soon as you change SelStart
          rtb.SelLength = lFindLength
          rtb.SelColor = lColor
   
          'Attempt to find the next match
          lFoundPos = rtb.Find(sFindString, _
            lFoundPos + lFindLength, , rtfNoHighlight)
        Wend
   
        'Restore the insertion point to its original
        'location and length
        rtb.SelStart = lOriginalSelStart
        rtb.SelLength = lOriginalSelLength
   
        'Return the number of matches
        HighlightWords = iMatchCount
   
      End Function
   
   

4. Choose Start from the Run menu, or press the F5 key to start the project. Click the Command button and you should see that both occurrences of the word "text" are now shown in red.

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