Enhanced Split Function for VB.NET

Category:

C#, VB.NET, ASP.NET

Type:

Snippets

Difficulty:

Intermediate

Author: Alastair Vance

Version Compatibility: Visual Basic.NET

More information:

This split function supports delimiters within text qualifiers (i.e. ignores them!).

Place code on a form. Place a listvew control on the form. Set up view style as "details".

You will need to write a sub to call previewfile using the following parameters:

ByRef lv As ListView (listview name), 
ByVal FileName As String (delimited file name), 
ByVal Delimiter As String (delimiter character), 
ByVal Qualifier As String (qualifier character), 
ByVal IgnoreLines As Integer (number of lines to ignore at beginning)

An Example:

Dim MySplitLine As Collection

MyString = "1,""My Text"",5061,""Some more, text."",839"
MySplitLine = SplitDelimitedLine(MyString, ",", """")

This example would return 5 sections.

1
My Text
5061
Some more, text.
839

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
' (None)

Code:

Imports System.IO

Public Class frmMyForm
    Inherits System.Windows.Forms.Form

Private Function SplitDelimitedLine(ByVal CurrentLine As String, ByVal Delimiter As String, ByVal Qualifier As String) As Collection

Dim i As Integer
        Dim SplitString As New Collection()
        Dim CountDelimiter As Boolean
        Dim Total As Integer
        Dim Ch As Char
        Dim Section As String

' We want to count the delimiter unless it is within the text qualifier
        CountDelimiter = True
        Total = 0
        Section = ""

For i = 1 To Len(CurrentLine)

Ch = Mid(CurrentLine, i, 1)
            Select Case Ch

Case Qualifier
                    If CountDelimiter Then
                        CountDelimiter = False
                    Else
                        CountDelimiter = True
                    End If

Case Delimiter
                    If CountDelimiter Then

' Add current section to collection
                        SplitString.Add(New MySection(Section))

Section = ""
                        Total = Total + 1

End If

Case Else

Section = Section & Ch

End Select

' Get the last field - as most files will not have an ending delimiter
        If CountDelimiter Then

' Add current section to collection
            SplitString.Add(New MySection(Section))

End If

SplitDelimitedLine = SplitString

End Function

Private Sub PreviewFile(ByRef lv As ListView, ByVal FileName As String, ByVal Delimiter As String, ByVal Qualifier As String, ByVal IgnoreLines As Integer)

Dim ts As StreamReader
        Dim CurrentLine As String
        Dim SampleLines(7) As String
        Dim i As Integer
        Dim j As Integer
        Dim MaxCols As Integer
        Dim SeparatedLine As Collection
        Dim section As MySection

lv.Columns.Clear()
        lv.Clear()

' Open the file and assign to a streamreader.
        ts = File.OpenText(FileName)

' Set maximum columns to 0
        MaxCols = 0
        j = 0

' Read only the first 8 lines
        ' to get a feel for how many columns is needed.
        For i = 1 To 8 + IgnoreLines

CurrentLine = ts.ReadLine

SeparatedLine = SplitDelimitedLine(CurrentLine, Delimiter, Qualifier)

' only treat/look at lines past ignore
            ' lines value...
            If i > IgnoreLines Then

' Keep line for later (data)
                SampleLines(j) = CurrentLine
                j = j + 1

' now that it's split out, count the columns.
                ' only keep the maximum value.
                If MaxCols < SeparatedLine.Count Then
                    MaxCols = SeparatedLine.Count
                End If

End If

' Add the required number of columns onto the listview
        For i = 1 To MaxCols

lv.Columns.Add("Column " & i, 100, HorizontalAlignment.Left)

' declare the listview item variables
        Dim oitem As ListViewItem
        Dim ositem As ListViewItem.ListViewSubItem

' Now add the data
        For i = 0 To 7

If SampleLines(i) <> "" Then

SeparatedLine = SplitDelimitedLine(SampleLines(i), Delimiter, Qualifier)

For j = 1 To SeparatedLine.Count

section = CType(SeparatedLine(j), MySection)

If j = 1 Then

oitem = New ListViewItem(section.Section)

Else

ositem = New ListViewItem.ListViewSubItem()
                        ositem.Text = section.Section
                        oitem.SubItems.Add(ositem)

End If

Next
                lv.Items.Add(oitem)

End If

' close the file
        ts.Close()
        section = Nothing

End Sub

End Class

Public Class MySection

Public Section As String
    Sub New(ByVal newName As String)
        Section = newName
    End Sub

End Class