Visual Basic

' Visual Basic .NET
Function PrevInstance() As Boolean
   If Ubound(Diagnostics.Process.GetProcessesByName(Diagnostics.Process.GetCurrentProcess.ProcessName)) > 0 Then
      Return True
   Else
      Return False
   End If
End Function

    Imports System.IO
    Imports System.Text
 
    Dim srcFile As New StreamReader("SourceFile.txt")
    Dim newFile As New StreamWriter("NewFile.txt")
    Dim inText As String
    Dim intLineCount As Integer = 1
 
    inText = srcFile.ReadLine()
    While Not inText Is Nothing
        If intLineCount <> 2 Then
            newFile.WriteLine(inText)
        Else
            newFile.WriteLine("New Text To Replace Line 2")
        End If
    End While
    srcFile.Close()
    newFile.Close()
 
    File.Delete("SourceFile.txt")
    File.Move("NewFile.txt", "SourceFile.txt")

<br />
Private Sub TextLineWriter(ByVal fileName As String, ByVal lineNumberToReplace As Integer, ByVal textToWrite As String)<br />
        Dim inFile As IO.StreamReader = IO.File.OpenText(fileName)<br />
        Dim tempString(-1) As String<br />
        Dim i As Byte<br />
<br />
        'read the file given and save each line into a new array element string<br />
        Do Until inFile.Peek = -1<br />
            ReDim Preserve tempString(tempString.Length)<br />
            tempString(tempString.Length - 1) = inFile.ReadLine<br />
        Loop<br />
        inFile.Close()<br />
<br />
        'determine if supplied 'numberToReplace' is valid with the current file,<br />
        'and correct the problem if so<br />
        If lineNumberToReplace - 1 > tempString.Length - 1 Then<br />
            lineNumberToReplace = tempString.Length<br />
        ElseIf lineNumberToReplace - 1 < 1 Then<br />
            lineNumberToReplace = 1<br />
        End If<br />
<br />
        'write the 'textToWrite' at the line number given<br />
        tempString(lineNumberToReplace - 1) = textToWrite<br />
<br />
        'create same file as given (overwriting it) and rewrite the entire file<br />
        Dim outFile As IO.StreamWriter = IO.File.CreateText(fileName)<br />
        For i = 0 To tempString.Length - 1<br />
            outFile.WriteLine(tempString(i))<br />
        Next<br />
        outFile.Close()<br />
    End Sub<br />