Regex.Match Method (String)
Searches the specified input string for the first occurrence of the regular expression specified in the Regex constructor.
Assembly: System (in System.dll)
The method returns the first substring that matches a regular expression pattern in an input string. For information about the language elements used to build a regular expression pattern, see Regular Expression Language - Quick Reference.
You can determine whether the regular expression pattern has been found in the input string by checking the value of the returned Match object's Success property. If a match is found, the returned Match object's Value property contains the substring from input that matches the regular expression pattern. If no match is found, its value is String.Empty.
This method returns the first substring in input that matches the regular expression pattern. You can retrieve subsequent matches by repeatedly calling the returned Match object's Match.NextMatch method. You can also retrieve all matches in a single method call by calling the Regex.Matches(String) method.
The RegexMatchTimeoutException exception is thrown if the execution time of the matching operation exceeds the time-out interval specified by the Regex.Regex(String, RegexOptions, TimeSpan) constructor. If you do not set a time-out interval when you call the constructor, the exception is thrown if the operation exceeds any time-out value established for the application domain in which the Regex object is created. If no time-out is defined in the Regex constructor call or in the application domain's properties, or if the time-out value is Regex.InfiniteMatchTimeout, no exception is thrown.
The following example finds regular expression pattern matches in a string, then lists the matched groups, captures, and capture positions.
Imports System.Text.RegularExpressions Module Example Public Sub Main() Dim text As String = "One car red car blue car" Dim pattern As String = "(\w+)\s+(car)" ' Instantiate the regular expression object. Dim r As Regex = new Regex(pattern, RegexOptions.IgnoreCase) ' Match the regular expression pattern against a text string. Dim m As Match = r.Match(text) Dim matchcount as Integer = 0 Do While m.Success matchCount += 1 Console.WriteLine("Match" & (matchCount)) Dim i As Integer For i = 1 to 2 Dim g as Group = m.Groups(i) Console.WriteLine("Group" & i & "='" & g.ToString() & "'") Dim cc As CaptureCollection = g.Captures Dim j As Integer For j = 0 to cc.Count - 1 Dim c As Capture = cc(j) Console.WriteLine("Capture" & j & "='" & c.ToString() _ & "', Position=" & c.Index) Next Next m = m.NextMatch() Loop End Sub End Module ' This example displays the following output: ' Match1 ' Group1='One' ' Capture0='One', Position=0 ' Group2='car' ' Capture0='car', Position=4 ' Match2 ' Group1='red' ' Capture0='red', Position=8 ' Group2='car' ' Capture0='car', Position=12 ' Match3 ' Group1='blue' ' Capture0='blue', Position=16 ' Group2='car' ' Capture0='car', Position=21
The regular expression pattern (\w+)\s+(car) matches occurrences of the word "car" along with the word that precedes it. It is interpreted as shown in the following table.
Match one or more word characters. This is the first capturing group.
Match one or more white-space characters.
Match the literal string "car". This is the second capturing group.