In what situations should regular expressions be used with caution in PHP programming?

Regular expressions should be used with caution in PHP programming when dealing with complex patterns or large amounts of data, as they can be resource-intensive and slow down the performance of your application. To mitigate this issue, you can optimize your regular expressions by making them more specific and efficient, avoiding unnecessary backtracking, and using built-in functions like `preg_match()` instead of `preg_match_all()` when possible. 

// Example of using a more specific regular expression pattern
$data = "Hello, World!";
if (preg_match('/^Hello/', $data)) {
    echo "String starts with 'Hello'";
} else {
    echo "String does not start with 'Hello'";
}

Keywords

regular expressions PHP programming caution security vulnerabilities input validation

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