check text only

function onlyText($s)
{
    $s2='';
$regex = '#[^a-z0-9_\',.@]#i';
$val = preg_replace($regex, ' ', $s);
    $a=explode(" ",$val);
    foreach($a as $v)$s2.=trim($v)." ";

$val = strtoupper($s2);
    return $val;
}