Find and Replace ... Found!

Find and Replace is one of the more useful features you can add to a control that holds text. I created this VB form to do a find first, find next, replace and replace all support.

The form was called as a modal form with .showDialog and a screen shot of just the form can be seen below. The Replace button is not enabled until Find First is clicked and the Replace All button is available without clicking on the find button. Find Next is also disabled until the first string is found. Bottom line: you must click on Find First or Replace All before using the other buttons. The program was written with Microsoft Visual Studio 2008 in Visual Basic.












Processing Logic

The program has been written to take advantage of some richtextbox control (mainForm.rtbBody) members (Find, Replace, SelectedText and SelectionColor) combined with some string functions. The program is reasonably straight forward perhaps with the exception of the richtextbox Find method which needs a search string, a starting point (in chars) to search,the length of the search term and the type of match (wholeword, case, etc. - see VB documentation for richtextbox.find method). The starting point of the find changes to start just after the last find so that find next and replace all can continue to search through the textbox.

You should be able to duplicate the form design and copy the code below into your application to test. Note: I had to truncate some lines with continuation characters to fit inside blog post window.

As always in this blog: Use this program example at your own risk. This code was created for educational purposes only. The author provides programming code "as is" and provides no warranty or guarantee. If you have questions, If you can email the author at gmarrer@gmail.com

Visual Basic.Net 2008 Source Code (with Program Comments)

Public Class findreplace
    'class instance variables
    Private findText As String ' find text
    Private replaceText As String ' replace text
    Private selectionStart, selectionLen, lastStart As Integer   'position variables for search


    Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
               Handles btnClose.Click
        'close form
        Me.Close()
    End Sub

    Private Sub btnFind_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
               Handles btnFind.Click
        'if no text in find textbook
        If txtFind.Text <> "' then" Then        
            'get ready to find the text
            findText = txtFind.Text
            'find text
            selectionStart = mainForm.rtbBody.Find(findText, RichTextBoxFinds.WholeWord)
            If selectionStart <>
                'text not found
                MessageBox.Show(findText & "  Text Not Found", "Warning", MessageBoxButtons.OK, _
                   MessageBoxIcon.Exclamation)
            Else
                'turn on replace and find next
                btnReplace.Enabled = True
                btnFindNext.Enabled = True
                'set new start point for continued search
                lastStart = selectionStart
                'start the selected text
                mainForm.rtbBody.SelectionStart = selectionStart
                'get len of selected text
                mainForm.rtbBody.SelectionLength = findText.Length
                'mark selected text red in richtextbox
                mainForm.rtbBody.SelectionColor = Color.Red
            End If
        Else
            'No text in Find input textbox
            MessageBox.Show("No find string entered. Please key in a value to find.", "Error", _
              MessageBoxButtons.OK, MessageBoxIcon.Error)
            txtFind.Focus()
        End If
    End Sub

    Private Sub btnReplace_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
               Handles btnReplace.Click
        'text in find textbox
        If txtFind.Text <> "" Then  ' 
            'text in replace textbox
            If txtReplace.Text <> "" Then
                'get replace text from textbox
                replaceText = txtReplace.Text
                'replace selected text found with replacement text
                mainForm.rtbBody.SelectedText = replaceText
                'mark selected text red in richtextbox
                mainForm.rtbBody.SelectionColor = Color.Red
            Else
                'text in replace textbox missing
                MessageBox.Show("No replace string entered. Please key in a value to find.", "Error", _
                     MessageBoxButtons.OK, MessageBoxIcon.Error)
                'put cursor in replace textbox
                txtReplace.Focus()
            End If
        Else
            'text in find textbox missing
            MessageBox.Show("No find string entered. Please key in a value to find.", "Error", _
                    MessageBoxButtons.OK, MessageBoxIcon.Error)
            'put cursor in find textbox
            txtFind.Focus()
        End If
    End Sub

    Private Sub btnFindNext_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
               Handles btnFindNext.Click
        'make sure find text is still there - mostly cosmetic
        If txtFind.Text <> "' then" Then
            'find text
            selectionStart = mainForm.rtbBody.Find(findText, lastStart + findText.Length, _
                   mainForm.rtbBody.TextLength, RichTextBoxFinds.WholeWord)
            'no more occurances
            If selectionStart <>
                MessageBox.Show(findText & "  No more occurances Found", "Warning", _
                    MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
            Else
                'select and mark the found text
                lastStart = selectionStart
                mainForm.rtbBody.SelectionStart = selectionStart
                mainForm.rtbBody.SelectionLength = findText.Length
                mainForm.rtbBody.SelectionColor = Color.Red
            End If
        Else
            'find input textbox is empty
            MessageBox.Show("No find string entered. Please key in a value to find.", "Error", _
                    MessageBoxButtons.OK, MessageBoxIcon.Error)
            'put cusor in find textbox
            txtFind.Focus()
        End If

    End Sub

    Private Sub btnReplaceAll_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) _
              Handles btnReplaceAll.Click
       
        'find and replace textboxes should not be empty
        If txtFind.Text <> "" And txtReplace.Text <> "" Then
            'store find text
            findText = txtFind.Text
            'store replace text
            replaceText = txtReplace.Text
            selectionStart = 0
            'find first occarance
            selectionStart = mainForm.rtbBody.Find(findText, RichTextBoxFinds.WholeWord)
            'set new start point for continued search
            lastStart = selectionStart
            'Text not found test
            If selectionStart <>
                MessageBox.Show(findText & "  Text Not Found", "Warning", MessageBoxButtons.OK, _
                       MessageBoxIcon.Exclamation)
            Else
                'text found replace text and mark with red
                lastStart = selectionStart
                mainForm.rtbBody.SelectionStart = selectionStart
                mainForm.rtbBody.SelectionLength = findText.Length
                mainForm.rtbBody.SelectedText = replaceText
                mainForm.rtbBody.SelectionColor = Color.Red
            End If
            'Are there more occurances - loop until none or -1
            While selectionStart >= 0
                'search for text
                selectionStart = mainForm.rtbBody.Find(findText, lastStart + findText.Length, _
                       mainForm.rtbBody.TextLength, RichTextBoxFinds.WholeWord)
                'if no more occrances exit 
                If selectionStart <>
                    Exit While
                Else
                    'set new start point for continued search
                    lastStart = selectionStart
                    'select text, replace and mark red
                    mainForm.rtbBody.SelectionStart = selectionStart
                    mainForm.rtbBody.SelectionLength = findText.Length
                    mainForm.rtbBody.SelectedText = replaceText
                    mainForm.rtbBody.SelectionColor = Color.Red
                End If
            End While

        Else
            'test must be in find and replace textboxes
            MessageBox.Show("Find and Replace Text must both be entered into Textboxes.", _
                      "Error", MessageBoxButtons.OK, MessageBoxIcon.Error)
            'place cursor in find textbox
            txtFind.Focus()
        End If
    End Sub
End Class