如何建立这个php数组？

Question

$items = "word1 word2 word3 word4"; 
$items = explode(" ", $items); 

$项目是我的数组，我怎么能有它变成这样

就像我怎样才能使WORD1中是一个关键的和值？

"word1" => "word1" 

Answer 1

$newArray =array_combine($items, $items);

Answer 2

foreach($items as $item) { 
$newArr[$item] = $item; 
} 

Answer 3

$items = "word1 word2 word3 word4"; 
$temp = explode(" ", $items); 
$result = array(); 
foreach ($temp as $value) { 
    $result[$value] = $value; 
}