3v4l.org

run code in 300+ PHP versions simultaneously
<?php $item = mb_convert_encoding( '¨l', 'ISO-8859-1', 'UTF-8' ); $encoding = 'UTF-8'; $ret = ''; $max = mb_strlen($item ?? '', $encoding); for ($i = 0; $i < $max; $i++) { $char = mb_substr($item, $i, 1, $encoding); $up = mb_strtoupper($char, $encoding); $low = mb_strtolower($char, $encoding); $ret .= ($up != $low) ? '[' . $up . $low . ']' : $char; } var_dump(utf8_decode($ret));
preferences:
29.81 ms | 410 KiB | 5 Q