php json卷曲执行

Question

我收到了json输出数组

 $res =    array(
        'first_name' => 'test',
        'last_name' => 'sam',
        'password' => 'Pass009',
        'email_id' => 'new12@gmail.com',
        'technologies'=>[{
"skill_name": "java",
"experience_in_year": 3,
"experience_in_month": 4
 }, {
"skill_name": "new java",
"experience_in_year": 3,
"experience_in_month": 4
 }],
        'mobile_num'=>'457896315');

这里的技术参数是二维数组。不，它不是一个字符串。因此，虽然进程$buffer = curl_exec($curl_handle);显示语法错误。

php code is

  $curl_handle = curl_init();
curl_setopt($curl_handle, CURLOPT_HTTPHEADER, array('X-API-KEY: key'));
curl_setopt($curl_handle, CURLOPT_URL, 'save url here');
curl_setopt($curl_handle, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($curl_handle, CURLOPT_POST, 1);
    curl_setopt($curl_handle, CURLOPT_POSTFIELDS, $res );     
   $buffer = curl_exec($curl_handle);
    curl_close($curl_handle);

$result = $buffer;
print_r($buffer);

但是它显示了语法错误。如何解决这个问题。