我如何只访问此PHP数组中的特定数组值

Question

I get this php array back from Apples APNS feedback service:

array(4) { 
    [0]=> string(64) "abc123" 
    [1]=> string(64) "def456"
    [2]=> array(3) { 
            ["timestamp"]=> int(1426717247) ["length"]=> int(32) ["devtoken"]=> string(64) "xyz987" 
    }
    [3]=> array(3) { 
            ["timestamp"]=> int(1426717247) ["length"]=> int(32) ["devtoken"]=> string(64) "xyz987" 
    }
}

How do I use php to loop over this array, and build a comma separated string of only the array elements that contain 'devtoken' item / value(s)?

UPDATE: I had been trying to do it with implode, and that may be do-able, but what I ended up using was based on the answer from Steve and looks like the following:

$deldevidstring='';
foreach($feedback_tokens as $element){
    if(is_array($element) && isset($element['devtoken'])){
        $deldevidstring .= $element['devtoken'] .',' ;
    }
}
if(strlen(trim($deldevidstring)) > 0){
   echo trim("delete these... " . $deldevidstring, ',');
}

Answer 1

iterate the array and build your string:

$string='';
foreach($array as $element){
    if(isset($element['devtoken'])){
        $string .=',' . $element['devtoken'];
    }
}
echo trim($string, ',');

Or implode a filtered array:

$string = implode(',', 
              array_filter(
                  array_map(
                      function($element){
                          return $element['devtoken']
                      }, 
                      $array
                  )
              )
          );

Answer 2

Check this out:

<?php

$str = "";

foreach($array as $arr)
{
    if(is_array($arr))
    {
        if(array_key_exists('devtoken', $arr))
        {
            $str = implode(",", $arr)."\n";
        }
    }
}

?>

Answer 3

Assuming you have set $records = the array you got back:

$string = '';

foreach ($records as $record) {
    if (isset($array['devtoken'])) {
        $string .= $array['devtoken'] . ', ';
    }
}
$string = substr($string, 0, -2);
echo $string;

There are no doubt more elegant ways to do this but for short and quick this seems to work.

Answer 4

No need to loop. With PHP >= 5.5.0:

$result = implode(',', array_column($array, 'devtoken'));

For earlier versions without array_column :

$result = implode(',', array_filter(array_map(function($v) { return $v['devtoken']; }, $array)));