Extract Links From WebPage using VB.Net Regular Expressions

Sub Extract_Links_From_WebPage()

Dim oReg As Regex

Dim oMat As Match

Dim sInputString As String

Dim sLink As String

sInputString = "some have links that direct to some html files

oReg = New Regex("href\s*=\s*(?:""(?<>[^""]*)(?<>\S+))", RegexOptions.Compiled Or RegexOptions.IgnoreCase)

oMat = oReg.Match(sInputString)

While oMat.Success

sLink = oMat.Groups("link").ToString

End While

End Sub

The above code uses Group class, which represents the results from a single capturing group. Because Group can capture zero, one, or more strings in a single match (using quantifiers), it contains a collection of Capture objects. Because Group inherits from Capture, the last substring captured can be accessed directly (the Group instance itself is equivalent to the last item of the collection returned by the Captures property).

Instances of Group are returned by indexing the GroupCollection object returned by the Groups property. The indexer can be a group number or the name of a capture group if the "(?< groupname >)" grouping construct is used. For example, in C# code you can use Match.Groups[groupnum] or Match.Groups["groupname"], or in Visual Basiccode you can use Match.Groups(groupnum) or Match.Groups("groupname").