Visual Basic

'Import missing system class libraries
Imports System.Text.RegularExpressions

Public Class frmMain

    Public Function SearchText(ByVal textToFind As String, _
    Optional ByVal startPosition As Integer = 0, Optional _
    ByVal endPosition As Integer = 0, Optional _
    ByVal highlightText As Boolean = True, Optional _
    ByVal matchCase As Boolean = False) As Integer

        '

        'Contains the return value of the search. IT it returns -1, then a match was not found.


        Dim i As Integer
        Dim LastWordinRichText As Integer
        Dim fromFirstWord As Integer
        LastWordinRichText = rtbContent.Text.LastIndexOf(textToFind)

        For fromFirstWord = 0 To LastWordinRichText
            txtIndexLocation.Text = startPosition

            If endPosition < 1 Then

                If Not matchCase Then
                    textToFind = textToFind.ToLower

                    Dim temp As String = rtbContent.Text.ToLower

                    i = temp.IndexOf(textToFind, startPosition, Me.Text.Length)
                Else
                    i = rtbContent.Text.IndexOf(textToFind, startPosition, Me.Text.Length)
                End If
            Else
                If matchCase = False Then
                    textToFind = textToFind.ToLower
                    Dim temp As String = rtbContent.Text.ToLower

                    i = temp.IndexOf(textToFind, startPosition, endPosition)

                Else
                    i = rtbContent.Text.IndexOf(textToFind, startPosition, endPosition)
                End If
            End If

            If i > -1 Then
                If highlightText Then
                    rtbContent.Focus()
                    rtbContent.SelectionStart = i
                    rtbContent.SelectionLength = textToFind.Length
                End If
                startPosition = startPosition + 1
            End If

            '
            'Returns the position where the text was found , otherwise it will report -1 which 
            'means that the search string was not found.

        Next
        Return i

    End Function

    Private Sub tsExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles tsExit.Click
        Me.Close()
    End Sub

    Private Sub btnSearch_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSearch.Click
        SearchText(txtSearch.Text)
    End Sub

    Private Sub NewSessionToolStripMenuItem_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles NewSessionToolStripMenuItem.Click

        'Open a new file dialog box  to browse for a text file which can be opened for analysis.

        'Variable declaration
        Dim Open As New OpenFileDialog()
        Dim myStreamReader As System.IO.StreamReader

        Open.Filter = "Plain Text Files (*.txt)|*.txt|All files (*.*)|*.*"
        Open.CheckFileExists = True
        Open.ShowDialog(Me)

        Try
            Open.OpenFile()
            myStreamReader = System.IO.File.OpenText(Open.FileName)
            rtbContent.Text = myStreamReader.ReadToEnd()
            Me.Text = "Text Editor - " & Open.FileName
        Catch ex As Exception
            ' Do nothing on Exception
        End Try

    End Sub

    Private Sub SaveCurrentSessionToolStripMenuItem_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles SaveCurrentSessionToolStripMenuItem.Click

        'Open a new dialog box to save current session file.

        Dim Save As New SaveFileDialog()
        Dim myStreamWriter As System.IO.StreamWriter
        Save.Filter = "Text Files (*.txt)|*.txt|All files (*.*)|*.*"
        Save.CheckPathExists = True
        Save.ShowDialog(Me)
        Try
            myStreamWriter = System.IO.File.AppendText(Save.FileName)
            myStreamWriter.Write(txtSearch.Text)
            myStreamWriter.Flush()
            Me.Text = "Text Editor - " & Save.FileName
        Catch ex As Exception
            ' Do nothing on Exception
        End Try
    End Sub
End Class