VB.NET Requires Chilkat v11.1.0+

Regular Expression with Capture Groups

See more Regular Expressions Examples

Note: Chilkat uses PCRE2. See PCRE2 Regular Expressions
Also see: PCRE2 Performance

Demonstrates the following PCRE2 regular expression:

See the sample code below.

Name:\s+(\w+)\s+(\w+),\s+Email:\s+(\S+)

And apply it to this string:

Name: John Smith, Email: john.smith@example.com

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Regex Components Explained

Part	Meaning	Matched Text
"Name:"	Matches the literal text "Name:"	"Name:"
"\s+"	Matches one or more whitespace characters (spaces, tabs, etc.)	(space)
"(\w+)"	Capture Group 1: One or more word characters ("a-zA-Z0-9_")	"John"
"\s+"	More whitespace	(space)
"(\w+)"	Capture Group 2: Another word (the last name)	"Smith"
","	A literal comma	","
"\s+"	Whitespace again	(space)
"Email:"	Matches the literal "Email:"	"Email:"
"\s+"	Whitespace	(space)
"(\S+)"	Capture Group 3: One or more non-whitespace characters	"john.smith@example.com"

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Matches for Your Example String

String:

"Name: John Smith, Email: john.smith@example.com"

Regex Match Groups:

Group	Captured Value
Group 1	"John"
Group 2	"Smith"
Group 3	"john.smith@example.com"

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Notes on Character Classes

• \w matches [a-zA-Z0-9_] — so it doesn’t include punctuation like a period.
• \S matches any non-whitespace character, so it’s good for capturing an email.

VB.NET

Dim success As Boolean = False

Dim subject As String = "Name: John Smith, Email: john.smith@example.com"
Dim pattern As String = "Name:\s+(\w+)\s+(\w+),\s+Email:\s+(\S+)"

Dim sb As New Chilkat.StringBuilder
sb.Append(subject)

Dim json As New Chilkat.JsonObject
json.EmitCompact = False

Dim timeoutMs As Integer = 2000
Dim numMatches As Integer = sb.RegexMatch(pattern,json,timeoutMs)
If (numMatches < 0) Then
    '  Probably an error in the regular expression.
    '  Suggestion: Use AI to help create and/or diagnose regular expressions.
    Debug.WriteLine(sb.LastErrorText)
    Exit Sub
End If


'  Examine the matches:
Debug.WriteLine(json.Emit())

'  This is the JSON with the match information.
'  See the JSON parsing code below to get the matched capture group values.

'  Important:  Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

'  {
'    "match": [
'      {
'        "group": [
'          {
'            "cap": "Name: John Smith, Email: john.smith@example.com",
'            "idx": 0,
'            "len": 47
'          },
'          {
'            "cap": "John",
'            "idx": 6,
'            "len": 4
'          },
'          {
'            "cap": "Smith",
'            "idx": 11,
'            "len": 5
'          },
'          {
'            "cap": "john.smith@example.com",
'            "idx": 25,
'            "len": 22
'          }
'        ]
'      }
'    ]
'  }

Dim cap As String
Dim i As Integer = 0
Dim matchCount As Integer = json.SizeOfArray("match")
While i < matchCount
    Debug.WriteLine("Match " & (i + 1) & ":")
    json.I = i
    Dim j As Integer = 0
    Dim numCaptureGroups As Integer = json.SizeOfArray("match[i].group")
    While j < numCaptureGroups
        json.J = j
        cap = json.StringOf("match[i].group[j].cap")
        Debug.WriteLine(j & ": " & cap)
        j = j + 1
    End While
    i = i + 1
End While

'  Capture group 0 always contains the entire match — that is, the portion of the input string that matches the full regular expression.

'  Output

'  Match 1:
'  0: Name: John Smith, Email: john.smith@example.com
'  1: John
'  2: Smith
'  3: john.smith@example.com