Xbase++ 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

---

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"

---

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"

---

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.

Xbase++

LOCAL nSuccess
LOCAL cSubject
LOCAL cPattern
LOCAL oSb
LOCAL oJson
LOCAL nTimeoutMs
LOCAL nNumMatches
LOCAL cCap
LOCAL i
LOCAL nMatchCount
LOCAL j
LOCAL nNumCaptureGroups

nSuccess := 0

cSubject := "Name: John Smith, Email: john.smith@example.com"
cPattern := "Name:\s+(\w+)\s+(\w+),\s+Email:\s+(\S+)"

oSb := CreateObject("Chilkat.StringBuilder")
oSb:Append(cSubject)

oJson := CreateObject("Chilkat.JsonObject")
oJson:EmitCompact := 0

nTimeoutMs := 2000
nNumMatches := oSb:RegexMatch(cPattern, oJson, nTimeoutMs)
IF (nNumMatches < 0)
    //  Probably an error in the regular expression.
    //  Suggestion: Use AI to help create and/or diagnose regular expressions.
    ? oSb:LastErrorText
    oSb:destroy()
    oJson:destroy()
    RETURN
ENDIF

//  Examine the matches:
? oJson: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
//          }
//        ]
//      }
//    ]
//  }

i := 0
nMatchCount := oJson:SizeOfArray("match")
DO WHILE i < nMatchCount
    ? "Match " + Str(i + 1) + ":"
    oJson:I := i
    j := 0
    nNumCaptureGroups := oJson:SizeOfArray("match[i].group")
    DO WHILE j < nNumCaptureGroups
        oJson:J := j
        cCap := oJson:StringOf("match[i].group[j].cap")
        ? Str(j) + ": " + cCap
        j := j + 1
    ENDDO
    i := i + 1
ENDDO

//  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

oSb:destroy()
oJson:destroy()