C#

Regular Expression with Multiple Matches and Capture Groups

See more Regular Expressions Examples

Demonstrates a regular expression with multiple matches and capture groups for each match.

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

C#

bool success = false;

string pattern = "Name:\\s+(\\w+)\\s+(\\w+),\\s+Email:\\s+(\\S+)";

Chilkat.StringBuilder sb = new Chilkat.StringBuilder();
bool crlf = true;
sb.AppendLine("Name: John Smith, Email: john.smith@example.com",crlf);
sb.AppendLine("Name: Jack Johnson, Email: jack.johnson@example.com",crlf);
sb.AppendLine("Name: Mary Adams, Email: mary.adams@example.com",crlf);

Debug.WriteLine(sb.GetAsString());

//  We have the following string:
//  Name: John Smith, Email: john.smith@example.com
//  Name: Jack Johnson, Email: jack.johnson@example.com
//  Name: Mary Adams, Email: mary.adams@example.com

Chilkat.JsonObject json = new Chilkat.JsonObject();
json.EmitCompact = false;

int timeoutMs = 2000;
int numMatches = sb.RegexMatch(pattern,json,timeoutMs);
if (numMatches < 0) {
    //  Probably an error in the regular expression.
    //  Suggestion: Use AI to help create and/or diagnose regular expressions.
    Debug.WriteLine(sb.LastErrorText);
    return;
}

//  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.

//  {
//    "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
//          }
//        ]
//      },
//      {
//        "group": [
//          {
//            "cap": "Name: Jack Johnson, Email: jack.johnson@example.com",
//            "idx": 49,
//            "len": 51
//          },
//          {
//            "cap": "Jack",
//            "idx": 55,
//            "len": 4
//          },
//          {
//            "cap": "Johnson",
//            "idx": 60,
//            "len": 7
//          },
//          {
//            "cap": "jack.johnson@example.com",
//            "idx": 76,
//            "len": 24
//          }
//        ]
//      },
//      {
//        "group": [
//          {
//            "cap": "Name: Mary Adams, Email: mary.adams@example.com",
//            "idx": 102,
//            "len": 47
//          },
//          {
//            "cap": "Mary",
//            "idx": 108,
//            "len": 4
//          },
//          {
//            "cap": "Adams",
//            "idx": 113,
//            "len": 5
//          },
//          {
//            "cap": "mary.adams@example.com",
//            "idx": 127,
//            "len": 22
//          }
//        ]
//      }
//    ]
//  }

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

string cap;
int i = 0;
int matchCount = json.SizeOfArray("match");
while (i < matchCount) {
    Debug.WriteLine("Match " + Convert.ToString(i + 1) + ":");
    json.I = i;
    int j = 0;
    int numCaptureGroups = json.SizeOfArray("match[i].group");
    while (j < numCaptureGroups) {
        json.J = j;
        cap = json.StringOf("match[i].group[j].cap");
        Debug.WriteLine(Convert.ToString(j) + ": " + cap);
        j = j + 1;
    }

    i = i + 1;
}

//  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
//  Match 2:
//  0: Name: Jack Johnson, Email: jack.johnson@example.com
//  1: Jack
//  2: Johnson
//  3: jack.johnson@example.com
//  Match 3:
//  0: Name: Mary Adams, Email: mary.adams@example.com
//  1: Mary
//  2: Adams
//  3: mary.adams@example.com