去除字符串中的空格和重复内容

<?php
error_reporting(E_ALL ^ E_NOTICE);
$word = "google baidu           baidu           ALOOL baidu    email     google    some     piman";
$word = preg_replace('//s+/', ' ', $word);
$_words = explode(' ', $word);
print_r($_words);
$words = array_unique($_words);
print_r($words);
/*
for($i=0;$i<count($words); $i++){
if($words[$i])
echo $i.$words[$i]."<br />";
}
*/
foreach($words as $w){
echo $w;
}
?>