enabling precise pattern matching and text manipulation Continuing on with our built-in functions with preg_match. To review the previous functions, read P101. https://blog.devgenius.io/php-p101-trim-htmlspecialchars-and-call-built-in-functions-7b4f25728db9 trim(),  ltrim() ,  rtrim() htmlspecialchars() __call() preg_match() filter_var() addslashes() str_replace() strlen() strtolower() strtoupper() ucfirst() strpos(), stripos(), strrpos(), strripos() Array Functions like: array_chunk(), array_diff(), array_key_exists(), array_key_first(), array_key_last(), array_map(), array_merge(), array_push(), array_sum(), asort(), arsort(), count(), in_array(), ksort(), krsort(), sort(), rsort(), shuffle(), sizeof(), is_array(), explode(), implode() Magic Methods like: __invoke(), __toString() Regex Intro I have been debating whether to even cover this one since it requires knowledge of regular expressions. We want to be as thorough as possible, so we’ll need to include some