Extract field lengths - vb.net

Question

I want to read fixed length files.
I know how to do this if I know the field lengths.
Using Reader As New Microsoft.VisualBasic.FileIO.TextFieldParser(filePath)
Reader.TextFieldType =
Microsoft.VisualBasic.FileIO.FieldType.FixedWidth
Reader.SetFieldWidths(8, 16, 16, 12, 14, 16) 'They are different in each file
Dim currentRow As String()
While Not Reader.EndOfData
Try
currentRow = Reader.ReadFields()
Dim currentField As String
For Each currentField In currentRow
MsgBox(currentField)
Next
Catch ex As Microsoft.VisualBasic.
FileIO.MalformedLineException
MsgBox("Line " & ex.Message &
"is not valid and will be skipped.")
End Try
End While
End Using
The problem is that I don't know the length of each field.
Is there a way to read the first line and get the Field lengths?

Answer 1

Since I have found the answer, I'll post it here in case someone will face the same problem.
I solved it using regex
'sRowData is the first line of the file
Dim pArLengths() As Integer = Nothing 'Array to store the lengths
Dim regex As New Regex("[^\W_\d]+", _
RegexOptions.IgnoreCase _
Or RegexOptions.Multiline _
Or RegexOptions.Singleline _
Or RegexOptions.IgnorePatternWhitespace)
Dim myMatches As MatchCollection = regex.Matches(sRowData)
ReDim pArLengths(myMatches.Count - 1)
For i = 0 To myMatches.Count - 1
Dim k As Integer
k = If(i < myMatches.Count - 1, myMatches(i + 1).Index, sRowData.Length)
pArLengths(i) = k - myMatches(i).Index
Next
I hope that someone will find it useful.