Group.Captures Property
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Gets a collection of all the captures matched by the capturing group, in innermost-leftmost-first order (or innermost-rightmost-first order if the regular expression is modified with the RegexOptions.RightToLeft option). The collection may have zero or more items.
Assembly: System (in System.dll)
Property Value
Type: System.Text.RegularExpressions.CaptureCollectionThe collection of substrings matched by the group.
If a quantifier is not applied to a capturing group, the collection returned by the Captures property contains a single Capture object that provides information about the same substring as the Group object. This is illustrated in the following example. It defines a regular expression, \b(\w+)\b, that extracts a single word from a sentence. The Group object captures the word "This", and the single object in the CaptureCollection contains information about the same capture.
Imports System.Text.RegularExpressions Module Example Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) Dim pattern As String = "\b(\w+)\b" Dim input As String = "This is one sentence." Dim match As Match = Regex.Match(input, pattern) If match.Success Then outputBlock.Text += String.Format("Matched text: {0}", match.Value) & vbCrLf For ctr As Integer = 1 To match.Groups.Count - 1 outputBlock.Text += String.Format(" Group {0}: {1}", ctr, match.Groups(ctr).Value) & vbCrLf Dim captureCtr As Integer = 0 For Each capture As Capture In match.Groups(ctr).Captures outputBlock.Text += String.Format(" Capture {0}: {1}", _ captureCtr, capture.Value) & vbCrLf captureCtr += 1 Next Next End If End Sub End Module ' The example displays the following output: ' Matched text: This ' Group 1: This ' Capture 0: This
The real utility of the Captures property occurs when a quantifier is applied to a capturing group so that the group captures multiple substrings in a single regular expression. In this case, the Group object contains information about the last captured substring, whereas the Captures property contains information about all the substrings captured by the group. In the following example, the regular expression \b(\w+\s*)+\. matches an entire sentence that ends in a period. The group (\w+\s*)+ captures the individual words in the collection. Because the Group collection contains information only about the last captured substring, it captures the last word in the sentence, "sentence". However, each word captured by the group is available from the collection returned by the Captures property.
Imports System.Text.RegularExpressions Module Example Public Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) Dim input As String = "This is a sentence. This is another sentence." Dim pattern As String = "\b(\w+\s*)+\." Dim match As Match = Regex.Match(input, pattern) If match.Success Then outputBlock.Text += String.Format("Matched text: {0}", match.Value) & vbCrLf For ctr As Integer = 1 To match.Groups.Count - 1 outputBlock.Text += String.Format(" Group {0}: {1}", ctr, match.Groups(ctr).Value) & vbCrLf Dim captureCtr As Integer = 0 For Each capture As Capture In match.Groups(ctr).Captures outputBlock.Text += String.Format(" Capture {0}: {1}", _ captureCtr, capture.Value) & vbCrLf captureCtr += 1 Next Next End If End Sub End Module ' The example displays the following output: ' Matched text: This is a sentence. ' Group 1: sentence ' Capture 0: This ' Capture 1: is ' Capture 2: a ' Capture 3: sentence