>This code used to run extremely fast before I moved to .NET Framework 4.
>
>

>        ' Return the specific line in a string
>        ' expN1 Line
>        Public Function MLine(ByVal tnLine As Integer) As Boolean
>            Dim lnLocation As Integer = 0
>            Dim loStringBuilderValueAdjusted As StringBuilder = New StringBuilder()
>
>            ' If the line requested is greather than the number of lines
>            If tnLine > nLine Then
>                cLine = ""
>                Return True
>            End If
>
>            ' If we are requesting the first ilne
>            If tnLine = 1 Then
>
>                ' See if we have more than one line
>                If nLine > 1 Then
>                    cLine = Mid(oStringBuilder.ToString, 1, InStr(oStringBuilder.ToString, oApp.cCR) - 1)
>                Else
>                    cLine = oStringBuilder.ToString
>                End If
>
>            Else
>
>                ' Make sure we are able to find a carriage return
>                lnLocation = oApp.At(oApp.cCR, oStringBuilder.ToString, tnLine - 1)
>                If lnLocation > 0 Then
>                    loStringBuilderValueAdjusted.Append(Mid(oStringBuilder.ToString, _
>                     oApp.At(oApp.cCR, oStringBuilder.ToString, tnLine - 1) + 2))
>
>                    ' If this is not the last line
>                    lnLocation = InStr(loStringBuilderValueAdjusted.ToString, oApp.cCR)
>                    If lnLocation > 0 Then
>                        cLine = Mid(loStringBuilderValueAdjusted.ToString, 1, _
>                         InStr(loStringBuilderValueAdjusted.ToString, oApp.cCR) - 1)
>                    Else
>                        cLine = loStringBuilderValueAdjusted.ToString
>                    End If
>
>                Else
>                    cLine = oStringBuilder.ToString
>                End If
>            End If
>
>            Return True
>        End Function
>

>
>Basically, this code returns a specific line from a string. It was originally designed to match the MLine() function of VFP. But, now, under the .NET Framework 4.0, this runs extremely slow. The greater the number of lines in the string, the more the duration in time it takes to find the line.
>
>So, basically, I read a directory having 1000 files. This goes into a string. Then, I use the number of carriage returns to locate the start of the string and get the line associated to it. But, I have to find another approach. Does anyone would have a better function to return a specific line from a string?


(1) You are constructing a StringBuilder each time you want a line. Can you work on the string directly ?
(2) I suspect the At() takes a long time - especially if you want the 900th line or so
(3) Instead of reading the directory into one string, can you read it into an array or strings ? That way the access to any line would be fast and you would not have the overhead of splitting each time you want a specific line