How do I return an array in a response

I'm trying to return an array in HTTP response. I'm thinking to return array as JSON objects. I'm doing echo json_encode($arr) but I get nothing in the response.

UPDATE: I'm running a version of PHP that does not have json_encode method. json_encode was introduced in PHP 5.2. So I guess question is how would you return an array without using json_encode?

     $arr = array();
    foreach($_POST['ids'] as $id)
    {
        $arr[$id] = $id;
    }   
    echo json_encode($arr);

    return;

Here are contents of my array:

array(18) {
  [156795]=开发者_开发问答>
  string(6) "156795"
  [156800]=>
  string(6) "156800"
  [4292]=>
  string(4) "4292"
  [796053]=>
  string(6) "796053"
  [660520]=>
  string(6) "660520"
 ...

---

Make sure to set the proper MIME type when sending back JSON:

header('Content-Type: application/json');
echo json_encode($arr);

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json_encode() requires PHP 5.2.0 or above. Make sure your host hasn't compiled PHP with the --disable-json flag. Both of these can be checked with the phpinfo() function. The code you've posted so far works fine for me.

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json encode should do it with no problems. When I pump that data into an array it works fine. Can you post some code for building the array? What version of PHP are you using?

---

plz use json validator to make sure ur json is correct

look I did this & it worked fine

 $arr = array();
 $i=0;
    while($i<10)
    {
        $arr[$i] = $i;
        $i++;
    }   
    echo json_encode($arr);

    return;