ok, lets say you have a long string, lets say i have an image (picture) file thats very long but i want to limit the amount of the string length i ca do this.

so if i have a string like this:

$long_string = 'zzy1p89tgzw1jwol3bk7p-xicpaiuugwwo7rxpppcml1rnurl6ailtp-2mpq96qej63sd7n.gif';

now, i only keep the last 15 characters of the file name to make it short i can use this
<?php
$max_filename_chars = 15;
$long_string = 'zzy1p89tgzw1jwol3bk7p-xicpaiuugwwo7rxpppcml1rnurl6ailtp-2mpq96qej63sd7n.gif';
$long_string = substr($long_string, - $max_filename_chars);
echo $long_string;
?>

so now the value of will be 96qej63sd7n.gif