<? 
 
$string = "lead on the way to l.a."; //this example string 
 
$str_list = array("l.a.","la","T.v.","t.v.","Tv","tv"); 
foreach($str_list as $key_str => $val_str) 
{ 
	if(preg_match("/\b$val_str\b/",$string)) 
	{ 
		$good_word = strtoupper($val_str); 
		$string = preg_replace("/\b$val_str\b/",$good_word,$string); 
	} 
} 
?>

<? 
 
preg_match("/\bl.a.\b/",$string) // this describe real process 
 
//or 
 
preg_replace("/\bl.a.\b/",$good_word,$string); 
 
?>