php limit upload file types and save uploaded files

The following code demonstrates how to obtain the files uploaded by users in php, and limit the file types to general image files, and finally save them to the server

$allowedExts = array("gif", "jpeg" , "jpg", "png");
$extension = end(explode(".", $_FILES["file"]["name"]));
if ((($_FILES["file"][ "type"] == "image/gif")
|| ($_FILES["file"]["type"] == "image/jpeg")
|| ($_FILES["file"]["type "] == "image/jpg")
|| ($_FILES["file"]["type"] == "image/pjpeg")
|| ($_FILES["file"]["type"] == "image/x-png")
|| ($_FILES["file"]["type"] == "image/png"))
&& ($_FILES["file"]["size"] < 20000)
&& in_array($extension, $allowedExts))
 {
 if ($_FILES["file"]["error"] > 0)
 {
 echo "Return Code: " . $_FILES[" file"]["error"] . "";
 }
 else
 {
 echo "Upload: " . $_FILES["file"]["name"] . "";
 echo "Type: " . $_FILES["file"]["type"] . "";
 echo "Size: " . ($_FILES["file"]["size"] / 1024) . " kB";
 echo "Temp file: " . $_FILES["file"]["tmp_name"] . "";

 if (file_exists("upload/" . $_FILES[" file"]["name"]))
 {
 echo $_FILES["file"]["name"] . " already exists. ";
 }
 else
 {
 move_uploaded_file($_FILES["file"][ "tmp_name"],
 "upload/" . $_FILES["file"]["name"]);
 echo "Stored in: " . "upload/" . $_FILES["file"]["name"] ;
 }
 }
 }
else
 {
 echo "Invalid file";
 }
?>

Upload the file and save it, php