What are some recommended tools for building and testing regular expressions in PHP?

Building and testing regular expressions in PHP can be challenging without the right tools. One recommended tool for building and testing regular expressions in PHP is an online regex tester like regex101.com. This tool allows you to input your regular expression and test it against sample text, providing real-time feedback on matches. Another helpful tool is the preg_match function in PHP, which allows you to test a regular expression against a string and see if it matches. This function can be used in combination with var_dump or print_r to debug and test regular expressions.

// Example of using preg_match to test a regular expression in PHP
$pattern = '/[0-9]+/';
$string = 'abc123def';

if (preg_match($pattern, $string)) {
    echo 'Match found!';
} else {
    echo 'No match found.';
}