Question

I have a file that has been generated by a server – I have no control over how this file is generated or formatted. I need to check each line begins with a string of set length (in this case 21 numerical chars). If a line doesn’t match that condition, I need to join it to the previous line and, after reading and correcting the whole file, save it. I am doing this for a lot of files in a directory.

So far I have:

       Dim rgx As New Regex("^[0-9]{21}$")

        Dim linesList As New List(Of String)(File.ReadAllLines(finfo.FullName))

        If linesList(0).Contains("BlackBerry Messenger") Then
            linesList.RemoveAt(0)
            For i As Integer = 0 To linesList.Count
                  If Not rgx.IsMatch(i.ToString) Then
                        linesList.Concat(linesList(i-1))
                 End If

            Next
        End If
        File.WriteAllLines(finfo.FullName, linesList.ToArray())[code]

There’s a for statement before and after that code block to loop over all files in the source directory, which works fine.

Hope this isn’t too bad to read :/

Answer 1

I didn’t think your solution was any good, you were failing on concatenating the lines. Here’s a different approach:

Dim rgx As New Regex("^[0-9]{21}")
Dim linesList As New List(Of String)(File.ReadAllLines(finfo.FullName))

' We will create a new list to store the new lines data
Dim newLinesList As New List(Of String)()

If linesList(0).Contains("BlackBerry Messenger") Then
    Dim i As Integer = 1
    Dim newLine As String
    While i < linesList.Count
        newLine = linesList(i)
        i += 1

        ' Keep going until the "real" line is over
        While i < linesList.Count AndAlso Not rgx.IsMatch(linesList(i))
            newLine += linesList(i)
            i += 1
        End While

        newLinesList.Add(newLine)
    End While
End If

File.WriteAllLines(finfo.FullName, newLinesList.ToArray())