How To Find and Highlight Text in the RichTextBox Control

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Article ID: 154884 - View products that this article applies to.
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SUMMARY

In many applications there is a function to search and highlight keywords in a text window. The RichTextBox control in Visual Basic 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.

REFERENCES

The Visual Basic Online Help and the Professional Features Manual in the Custom Control Section, p.329-362.

Properties

Article ID: 154884 - Last Review: July 1, 2004 - Revision: 4.1
APPLIES TO
  • Microsoft Visual Basic 5.0 Learning Edition
  • Microsoft Visual Basic 6.0 Learning Edition
  • Microsoft Visual Basic 5.0 Professional Edition
  • Microsoft Visual Basic 6.0 Professional Edition
  • Microsoft Visual Basic 5.0 Enterprise Edition
  • Microsoft Visual Basic 6.0 Enterprise Edition
  • Microsoft Visual Basic 4.0 Standard Edition
  • Microsoft Visual Basic 4.0 Professional Edition
  • Microsoft Visual Basic 4.0 32-Bit Enterprise Edition
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