Why curl prints XML response?

I'm using curl to do post request, for some reason it prints xml response, which is something that I don't want to happend. how can I get rid of this behaviour?

/**
*   Send post request
**/
function post_request($sendHtt开发者_C百科pUrl, $data) {

    $ch = curl_init($sendHttpUrl);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: text/xml'));      
    curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);       
    $response = curl_exec($ch);
    curl_close($ch);

    return $response;
}

You've set the RETURNTRANSFER flag on the wrong variable. Alter $curl to $ch.

You have a typo in line: "curl_setopt($curl, CURLOPT_RETURNTRANSFER, true); "

It should read:

curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);