Example: (Send a post request with specific header):

$params = array(
    'client_id' => $this->clientID, 
    'redirect_uri' => $this->redirectURI
);

//Notice: value for header array is strings, not key/value pairs.
$request = array(
    CURLOPT_HTTPHEADER => array(
        'Content-type: application/x-www-form-urlencoded',
        'param1:value1',
        'param2:value2'
    ), 
    CURLOPT_POST => true, 
    CURLOPT_POSTFIELDS => http_build_query($params), 
    CURLOPT_RETURNTRANSFER => true //Important!
);

$ch = curl_init('http://REQUEST URL');
curl_setopt_array($ch, $request);
$result = curl_exec($ch);
//$info = curl_getinfo($ch);
$data = json_decode($result);

Error Handling

顯示錯誤: curl_error($ch)

SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed

如果出現上面這個問題:

Solution 1:
CURLOPT_SSL_VERIFYPEER => false
http://blog.kejyun.com/2012/12/Facebook-PHP-SDK-SSL-Certificate-Problem-Solution.html

Solution 2: 表示Cert有問題，請參考:
http://davidwalsh.name/php-ssl-curl-error 
http://unitstep.net/blog/2009/05/05/using-curl-in-php-to-access-https-ssltls-protected-sites/ 

總之要加上下面這個參數:
curl_setopt($ch,CURLOPT_CAINFO,’d:\path\cert.pem’);
cert.pem下載網址: http://curl.haxx.se/docs/caextract.html

Reference:

1. http://www.inote.tw/2009/04/php-curl.html