PHP ctt check extension + echo string to maillist

[eele]

if(isset($_POST['upload'])){
    $path = "upload/";
    $newname = $path.basename($_FILES['ctt']['name']);
    $rctt = str_replace('ctt','txt',$newname); //Replace .ctt to .txt
    if(move_uploaded_file($_FILES['ctt']['tmp_name'],$rctt))
    {
        echo'Uploaded^^';
    }
    else
    {
        echo'This is a failure..';
    }
} 

How I can check if the extension is ctt? And if I uploaded the file and I wanna read it.
I do

#sample
$file = "upload/test.txt"; //Example test.txt :)
$f = fopen($file, "r");
$string = fread($f,filesize($file));
echo $string; 

It echo's
example@hotmail.com example@live.nl

There is much space between the two mails. Also I wanted to echo it like

example@hotmail.com,example@live.nl,...e2@hotmail.com

Like a mail list..
You guys should know what I wanted with this:P

[MentaL]

[PsychoJr]

use this function to find the extension .. then u can make an if/else statement

    function findexts($filename)
    {
        $filename = strtolower($filename) ;
        $exts = split("[/\\.]", $filename) ;
        $n = count($exts)-1;
        $exts = $exts[$n];
        return $exts;
    } 

[eele]

Thanks:) I already fixed the extension check, only need to know how to make a mailinglist of the string:P

[jMerliN]

Thanks:) I already fixed the extension check, only need to know how to make a mailinglist of the string:P

explode+join.

[eele]

explode+join.

Thanks, I'm gonna make my script complete later on the day:P