Wordpress init_curl() function error

I am trying to make a wordpress plugin that fetches twitter tweets via API and echoes them on page if a shortcode [twitter] is inserted on a page.

I am getting an error:

"FATAL ERROR: CALL TO UNDEFINED FUNCTION CURL_INIT() IN C:\WAMP\WWW\WP\WP-CONTENT\PLUGINS\PLOG\PLUGIN.PHP ON LINE 45"

There is no syntax error in the code neither s there any logical error.

Here is the code:

<?php
/* Plugin Name: Testing a Plugin
 * Plugin URI: http://www.wordpress.com
 * Description: Just Testing out a plugin.
 * Author: Knooww
 * Author URI: http://www.wordpress.com
 */
?>
<?php
//limit calls to API..
// Save data in cache, refresh content after an hour

add_shortcode('twitter',  function ($atts,$content){

          $atts = shortcode_atts(array('username'=>'Default-Username',
                                 'content' =>!empty($content) ? $content:'Follow me on twitter',
                                 'show_tweets'=>'false',
                                 'tweet_reset_time'=>10, //time to refresh fetch of tweets
                                 'num_tweets'=>5

            ),$atts);


    extract($atts);
    if($show_tweets){

        $tweets = fetch_tweets($num_tweets,$username,$tweet_reset_time);
    }


//return '<a href="http://www.twitter.com/'.$username.'">'.$content.'</a>';

});// end add_shortcode

function fetch_tweets($num_tweets,$username,$tweet_reset_time){

    $tweets = curl("https://api.twitter.com/1/statuses/user_timeline.json?include_entities=true&include_rts=true&screen_name='$username'&count=2");
  print_r($tweets);  

}

function curl($url){

$c = curl_init($url);
curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($c, CURLOPT_CONNECTTIMEOUT, 3);
curl_setopt($c, CURLOPT_TIMEOUT, 5);
return json_decode(curl_exec($c));



}


?>

Please let me know what I am missing.