Visual FoxPro

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.

Visual FoxPro

LOCAL lnSuccess
LOCAL lcSubject
LOCAL lcPattern
LOCAL loSb
LOCAL loJson
LOCAL lnTimeoutMs
LOCAL lnNumMatches
LOCAL lcCap
LOCAL i
LOCAL lnMatchCount
LOCAL j
LOCAL lnNumCaptureGroups

lnSuccess = 0

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

loSb = CreateObject('Chilkat.StringBuilder')
loSb.Append(lcSubject)

loJson = CreateObject('Chilkat.JsonObject')
loJson.EmitCompact = 0

lnTimeoutMs = 2000
lnNumMatches = loSb.RegexMatch(lcPattern,loJson,lnTimeoutMs)
IF (lnNumMatches < 0) THEN
    * Probably an error in the regular expression.
    * Suggestion: Use AI to help create and/or diagnose regular expressions.
    ? loSb.LastErrorText
    RELEASE loSb
    RELEASE loJson
    CANCEL
ENDIF

* Examine the matches:
? loJson.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
lnMatchCount = loJson.SizeOfArray("match")
DO WHILE i < lnMatchCount
    ? "Match " + STR(i + 1) + ":"
    loJson.I = i
    j = 0
    lnNumCaptureGroups = loJson.SizeOfArray("match[i].group")
    DO WHILE j < lnNumCaptureGroups
        loJson.J = j
        lcCap = loJson.StringOf("match[i].group[j].cap")
        ? STR(j) + ": " + lcCap
        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

RELEASE loSb
RELEASE loJson