Programming Visual Basic .NET, Second Edition

The Regex Class

The .NET Framework provides an object-oriented approach to regular expression matching and replacement.

The Framework Class Library namespace System.Text.RegularExpressions is the home to all the .NET Framework objects associated with regular expressions. The central class for regular expression support is Regex, which represents an immutable, compiled regular expression. Example 10-9 rewrites Example 10-8 to use regular expressions and thus solve the problem of searching for more than one type of delimiter.

Example 10-9. Using the Regex class for regular expressions

Option Strict On
Imports System
Imports System.Text
Imports System.Text.RegularExpressions

Namespace RegularExpressions

    Class Tester

        Public Sub Run( )
            Dim s1 As String = "One,Two,Three Liberty Associates, Inc."
            Dim theRegex As New Regex(" |, |,")
            Dim sBuilder As New StringBuilder( )
            Dim id As Integer = 1

            Dim subString As String
            For Each subString In theRegex.Split(s1)
                id = id + 1
                sBuilder.AppendFormat("{0}: {1}"  _
                  & Environment.NewLine, id, subString)
            Next subString
            Console.WriteLine("{0}", sBuilder.ToString( ))
        End Sub 'Run

        Public Shared Sub Main( )
            Dim t As New Tester( )
            t.Run( )
        End Sub 'Main
    End Class 'Tester
End Namespace 'RegularExpressions

Output:
1: One
2: Two
3: Three
4: Liberty
5: Associates
6: Inc.

Example 10-9 begins by creating a string, s1, identical to the string used in Example 10-8:

Dim s1 As String = "One,Two,Three Liberty Associates, Inc."

and a regular expression that will be used ...