Objective-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

Objective-C

#import <NSString.h>
#import <CkoStringBuilder.h>
#import <CkoJsonObject.h>

BOOL success = NO;

NSString *pattern = @"Name:\\s+(\\w+)\\s+(\\w+),\\s+Email:\\s+(\\S+)";

CkoStringBuilder *sb = [[CkoStringBuilder alloc] init];
BOOL crlf = YES;
[sb AppendLine: @"Name: John Smith, Email: john.smith@example.com" crlf: crlf];
[sb AppendLine: @"Name: Jack Johnson, Email: jack.johnson@example.com" crlf: crlf];
[sb AppendLine: @"Name: Mary Adams, Email: mary.adams@example.com" crlf: crlf];

NSLog(@"%@",[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

CkoJsonObject *json = [[CkoJsonObject alloc] init];
json.EmitCompact = NO;

int timeoutMs = 2000;
int numMatches = [[sb RegexMatch: pattern json: json timeoutMs: [NSNumber numberWithInt: timeoutMs]] intValue];
if (numMatches < 0) {
    // Probably an error in the regular expression.
    // Suggestion: Use AI to help create and/or diagnose regular expressions.
    NSLog(@"%@",sb.LastErrorText);
    return;
}

// Examine the matches:
NSLog(@"%@",[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.

NSString *cap = 0;
int i = 0;
int matchCount = [[json SizeOfArray: @"match"] intValue];
while (i < matchCount) {
    NSLog(@"%@%d%@",@"Match ",i + 1,@":");
    json.I = [NSNumber numberWithInt: i];
    int j = 0;
    int numCaptureGroups = [[json SizeOfArray: @"match[i].group"] intValue];
    while (j < numCaptureGroups) {
        json.J = [NSNumber numberWithInt: j];
        cap = [json StringOf: @"match[i].group[j].cap"];
        NSLog(@"%d%@%@",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.co