foreach (glob("t_*.jpg") as $filename) {
    echo "$filename size " . filesize($filename) . "\n";
}

这意味着:

foreach (glob("$dir/t_*.jpg") as $filename) {
    echo "$filename size " . filesize($filename) . "\n";
}

另请参阅:

http://ca2.php.net/manual/en/function .glob.php