Visual Basic 6.0

Regular Expression with Multiple Matches and Named Capture Groups

See more Regular Expressions Examples

Demonstrates regular expressions with named capture groups and multiple matches. Visual Basic 6.0

Dim success As Long
success = 0

Dim sb As New ChilkatStringBuilder
Dim crlf As Long
crlf = 1
success = sb.AppendLine("Name: John Smith",crlf)
success = sb.AppendLine("Name: Jack Johnson",crlf)
success = sb.AppendLine("Name: Mary Adams",crlf)

Debug.Print sb.GetAsString()

' We have the following string:
' Name: John Smith
' Name: Jack Johnson
' Name: Mary Adams

Dim pattern As String
pattern = "Name:\s+(?<first>\w+)\s+(?<last>\w+)"
Dim json As New ChilkatJsonObject
json.EmitCompact = 0

Dim timeoutMs As Long
timeoutMs = 2000
Dim numMatches As Long
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.
    Debug.Print sb.LastErrorText
    Exit Sub
End If

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

' 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": "Name: John Smith",
'           "idx": 0,
'           "len": 16
'         },
'         {
'           "cap": "John",
'           "idx": 6,
'           "len": 4
'         },
'         {
'           "cap": "Smith",
'           "idx": 11,
'           "len": 5
'         }
'       ]
'     },
'     {
'       "group": [
'         {
'           "cap": "Name: Jack Johnson",
'           "idx": 18,
'           "len": 18
'         },
'         {
'           "cap": "Jack",
'           "idx": 24,
'           "len": 4
'         },
'         {
'           "cap": "Johnson",
'           "idx": 29,
'           "len": 7
'         }
'       ]
'     },
'     {
'       "group": [
'         {
'           "cap": "Name: Mary Adams",
'           "idx": 38,
'           "len": 16
'         },
'         {
'           "cap": "Mary",
'           "idx": 44,
'           "len": 4
'         },
'         {
'           "cap": "Adams",
'           "idx": 49,
'           "len": 5
'         }
'       ]
'     }
'   ]
' }

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

Dim idx_first As Long
idx_first = json.IntOf("named.first")
Dim idx_last As Long
idx_last = json.IntOf("named.last")

Dim i As Long
i = 0
Dim matchCount As Long
matchCount = json.SizeOfArray("match")
Do While i < matchCount
    Debug.Print "Match " & (i + 1) & ":"
    json.I = i

    json.J = idx_first
    Debug.Print "first: " & json.StringOf("match[i].group[j].cap")

    json.J = idx_last
    Debug.Print "first: " & json.StringOf("match[i].group[j].cap")

    Debug.Print ""
    i = i + 1
Loop

' Output is: 

' Match 1:
' first: John
' first: Smith
' 
' Match 2:
' first: Jack
' first: Johnson
' 
' Match 3:
' first: Mary
' first: Adams