Classic ASP Requires Chilkat v11.1.0+

Regular Expression with Named Capture Groups

Demonstrates regular expressions with named capture groups.

See the sample code below.

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

In PCRE2, named capture groups allow you to assign a name to a capturing group, making it easier to reference by name instead of number.

Syntax

(?<name>pattern)

(?'name'pattern)

Example

(?<first>\w+)\s+(?<last>\w+)

Applied to:

"John Smith"

Produces:

first: John
last: Smith

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Classic ASP

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

subject = "John Smith"
pattern = "(?<first>\w+)\s+(?<last>\w+)"

set sb = Server.CreateObject("Chilkat.StringBuilder")
success = sb.Append(subject)

set json = Server.CreateObject("Chilkat.JsonObject")
json.EmitCompact = 0

timeoutMs = 2000
numMatches = 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.
    Response.Write "<pre>" & Server.HTMLEncode( sb.LastErrorText) & "</pre>"
    Response.End
End If

'  Examine the matches:
Response.Write "<pre>" & Server.HTMLEncode( json.Emit()) & "</pre>"

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

'  {
'    "named": {
'      "first": 1,
'      "last": 2
'    },
'    "match": [
'      {
'        "group": [
'          {
'            "cap": "John Smith",
'            "idx": 0,
'            "len": 10
'          },
'          {
'            "cap": "John",
'            "idx": 0,
'            "len": 4
'          },
'          {
'            "cap": "Smith",
'            "idx": 5,
'            "len": 5
'          }
'        ]
'      }
'    ]
'  }

'  The capture group index is obtained by looking up the name in the JSON result.
'  For example:

json.I = json.IntOf("named.first")
Response.Write "<pre>" & Server.HTMLEncode( "first: " & json.StringOf("match[0].group[i].cap")) & "</pre>"

json.I = json.IntOf("named.last")
Response.Write "<pre>" & Server.HTMLEncode( "last: " & json.StringOf("match[0].group[i].cap")) & "</pre>"

'  Output is: 

'  first: John
'  last: Smith

%>
</body>
</html>