How can one troubleshoot and debug issues with regular expressions not matching in PHP?

If regular expressions are not matching in PHP, one way to troubleshoot and debug the issue is to use a tool like regex101.com to test and validate the regular expression pattern. Additionally, check for any syntax errors or incorrect usage of metacharacters in the regular expression. It's also helpful to use functions like preg_match() with proper error handling to identify any issues with the matching process. 

$pattern = '/[0-9]+/';
$string = 'abc123def';

if (preg_match($pattern, $string, $matches)) {
    echo 'Match found: ' . $matches[0];
} else {
    echo 'No match found';
}

Keywords

regular expressions debugging troubleshooting PHP functions error types

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