- implode: documentation ( source)
- preg_split: documentation ( source)
- array_diff: documentation ( source)
- range: documentation ( source)
<?php
$sentence = 'subdermatoglyphic';
$alphabet = range('a', 'z');
echo implode(
array_diff(
$alphabet,
preg_split(
'~[^a-z]*~i',
$sentence,
0,
PREG_SPLIT_NO_EMPTY
)
)
);