获取数组中的key值

<?php

$arr = array(

‘book‘ => 1,

‘data‘ => ‘data‘,

‘music‘ => ‘music‘,

‘img‘ => ‘img‘,

‘software‘ => ‘software‘,

);

ob_start();

foreach ($arr as $key => $valuse){

$keys[] = $key;

echo $key."<br />";

}

$keys_array = ob_get_contents();

ob_end_clean();

/*

echo "<pre>";

//var_dump($keys);

print_r($keys);

*/

echo $keys_array;