How to call json from php -

i have written php code should print response of json call. getting null output. have checked json call working fine restclient.

here code

<?php      $username = "user";     $password = "password";      $postdata = array(             'username' => $username,             'password' => $password,             'msisdn' => "111111111"             );      $ch = curl_init('http://ip:<port>/xxx/yyy/zzz');      curl_setopt_array($ch, array(     curlopt_post => true,     curlopt_returntransfer => true,     curlopt_httpheader => array(         'content-type: application/json'     ),     curlopt_postfields => json_encode($postdata)     ));      // send request     $response = curl_exec($ch);      // check errors     if($response === false){     die(curl_error($ch));     }      // decode response     $responsedata = json_decode($response, true);      // print date response     echo $responsedata['published'];      var_dump($responsedata);      ?> 

thanks in advance.

try:

$responsedata = json_decode($response, true); if (json_last_error() !== json_error_none) {     throw new \runtimeexception('invalid json.'); }