compare and merge multiple files the text file using VB.NET - vb.net

Question

I have a multiple text files that I need to merge. but I need to compare the reference number before merge it.
below is the text file
Text 1
001Email
002Video
003SocialNetwork
Text 2
001Gmail
001Yahoo
002Youtube
002Metacafe
003Facebook
003Myspace
Text 3
www.gmail.com001
www.yahoo.com001
www.youtube.com002
www.myspace.com002
www.facebook.com003
www.myspace.com003
Output
001Email
001Gmail
www.gmail.com001
001Yahoo
wwww.yahoo.com001
002Video
002Youtube
www.youtube.com002
002Metacafe
www.metacafe.com002
003SocialNetwork
003Facebook
www.facebook.com003
003Myspace
www.myspace.com003
What will be the fastest way to deal it read line by line to compare. the text file consist of thousand of line

Answer 1

Here's what might possibly be an overly complex solution. The comments in the code should explain everything hopefully. The output doesn't match exactly what you have because I don't know how much order is important for everything. It sorts everything first by the reference number and then by the text portion of the string (excluding www.). The results you posted were in reference number order and then file parsing order and then alphabetical (002Metacafe came after 002Video). Let me know if that's important.
Option Explicit On
Option Strict On
Imports System.IO
Imports System.Text.RegularExpressions
Public Class Form1
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
''//List of files to process
Dim Files As New List(Of String)
Files.Add(Path.Combine(My.Computer.FileSystem.SpecialDirectories.Desktop, "Text1.txt"))
Files.Add(Path.Combine(My.Computer.FileSystem.SpecialDirectories.Desktop, "Text2.txt"))
Files.Add(Path.Combine(My.Computer.FileSystem.SpecialDirectories.Desktop, "Text3.txt"))
''//Will hold the current line being read
Dim Line As String
''//Holds our main collection of data
Dim MyData As New List(Of Data)
''//Loop through each file
For Each F In Files
''//Open the file for reading
Using FS As New FileStream(F, FileMode.Open, FileAccess.Read, FileShare.Read)
Using SR As New StreamReader(FS)
''//Read each line
Line = SR.ReadLine()
Do While Line IsNot Nothing
''//The data constructor handles parsing of the line
MyData.Add(New Data(Line))
''//Read next line
Line = SR.ReadLine()
Loop
End Using
End Using
Next
''//Our data implements IComparable(Of Data) so we can just sort the list
MyData.Sort()
''//Output our data
For Each D In MyData
Trace.WriteLine(D)
Next
Me.Close()
End Sub
End Class
Public Class Data
Implements IComparable(Of Data)
''//Our RegEx pattern for looking for a string that either starts or ends with numbers
Private Shared ReadOnly Pattern As String = "^(?<RefStart>\d+)?(?<Text>.*?)(?<RefEnd>\d+)?$"
Public Text As String ''//The _text_ portion of the data
Public Reference As String ''//The reference number stored as text
Public ReferenceAtStart As Boolean ''//Whether the reference number was found at the start or end of the line
Public ReadOnly Property ReferenceAsNum() As Integer ''//Numeric version of the reference number for sorting
Get
Return Integer.Parse(Me.Reference)
End Get
End Property
Public ReadOnly Property TextComparable() As String ''//Remove the www for sorting
Get
Return Me.Text.Replace("www.", "")
End Get
End Property
Public Sub New(ByVal line As String)
''//Sanity check
If String.IsNullOrEmpty(line) Then Throw New ArgumentNullException("line")
''//Parse the line
Dim M = Regex.Match(line, Pattern)
If M Is Nothing Then Throw New ArgumentException("Line does not conform to expected pattern")
''//If the RefStart has a value then the number is at the beginning of the string
If M.Groups("RefStart").Success Then
Me.ReferenceAtStart = True
Me.Reference = M.Groups("RefStart").Value
Else ''//Otherwise its at the end
Me.ReferenceAtStart = False
Me.Reference = M.Groups("RefEnd").Value
End If
Me.Text = M.Groups("Text").Value
End Sub
Public Function CompareTo(ByVal other As Data) As Integer Implements System.IComparable(Of Data).CompareTo
''//Compare the reference numbers first
Dim Ret = Me.ReferenceAsNum.CompareTo(other.ReferenceAsNum)
''//If they are the same then compare the strings
If Ret = 0 Then Ret = String.Compare(Me.TextComparable, other.TextComparable, StringComparison.InvariantCultureIgnoreCase)
Return Ret
End Function
Public Overrides Function ToString() As String
''//Reproduce the original string
If Me.ReferenceAtStart Then
Return String.Format("{0}{1}", Me.Reference, Me.Text)
Else
Return String.Format("{1}{0}", Me.Reference, Me.Text)
End If
End Function
End Class