3v4l.org

run code in 300+ PHP versions simultaneously
<?php $str1 ="Lorem ipsum, or lipsum as it is sometimes known, is dummy text used in laying out print, <i>graphic</i> or web designs."; $str2 = "laying out print, <i>graphic</i>"; $regex = preg_replace('/\s+/', '\s+', preg_quote($str2, '/')); echo preg_replace("/$regex/iu", '<span style="color:red">$0</span>', $str1);

preferences:
157.82 ms | 405 KiB | 5 Q