PHP Mail, CC Field - php

Question

How can I include a CC field in this function?
function mail_attachment($filename, $path, $mailto, $from_mail, $from_name, $replyto, $subject, $message) {
$file = $path.$filename;
$file_size = filesize($file);
$handle = fopen($file, "r");
$content = fread($handle, $file_size);
fclose($handle);
$content = chunk_split(base64_encode($content));
$uid = md5(uniqid(time()));
$name = basename($file);
$header = "From: ".$from_name." <".$from_mail.">\r\n";
$header .= "Reply-To: ".$replyto."\r\n";
$header .= "MIME-Version: 1.0\r\n";
$header .= "Content-Type: multipart/mixed; boundary=\"".$uid."\"\r\n\r\n";
$header .= "This is a multi-part message in MIME format.\r\n";
$header .= "--".$uid."\r\n";
$header .= "Content-Type: text/html; charset=iso-8859-1\n";
$header .= "Content-Transfer-Encoding: 7bit\r\n\r\n";
$header .= $message."\r\n\r\n";
$header .= "--".$uid."\r\n";
$header .= "Content-Type: application/octet-stream; name=\"".$filename."\"\r\n"; // use different content types here
$header .= "Content-Transfer-Encoding: base64\r\n";
$header .= "Content-Disposition: attachment; filename=\"".$filename."\"\r\n\r\n";
$header .= $content."\r\n\r\n";
$header .= "--".$uid."--";
if (mail($mailto, $subject, "", $header)) {
echo "OK"; // or use booleans here
} else {
echo "ERROR!";
}
}

Answer 1

Add this while declaring headers:
$headers .= 'Cc: somebody#example.com' . "\r\n";

Answer 2

Add $header .= "CC: ".$cc."\r\n"; after the Reply-To-line.
http://www.w3schools.com/PHP/func_mail_mail.asp

Answer 3

Please don't build your own MIME emails. Use something like PHPMailer instead. Far easier to use and less brittle. Adding a CC with that is as simple as:
$mail = new PHPMailer();
$mail->AddCC('somebody#example.com');