// function to upload a file;
	function uploadFile($file,$expected_ext,$expected_size,$upload_dir){

		$upload_errors = array(

		UPLOAD_ERR_OK 			=> "No errors.",
		UPLOAD_ERR_INI_SIZE  	=> "Larger than upload_max_filesize.",
		UPLOAD_ERR_FORM_SIZE 	=> "Larger than form MAX_FILE_SIZE.",
		UPLOAD_ERR_PARTIAL 		=> "Partial upload.",
		UPLOAD_ERR_NO_FILE 		=> "No file.",
		UPLOAD_ERR_NO_TMP_DIR   => "No temporary directory.",
		UPLOAD_ERR_CANT_WRITE   => "Can't write to disk.",
		UPLOAD_ERR_EXTENSION 	=> "File upload stopped by extension."
		);

		$problem = "";

		@mkdir($upload_dir,0777);

		$name 	= $file['name'];
		$tmp 	= $file['tmp_name'];
		$error	= $file['error'];
		$size 	= $file['size'];

		//$expected_ext = array('jpg','jpeg','png');
		$expected_size = ($expected_size*1024);

		//you can use pathinfo function
		$x = explode('.',strtolower($name));
		$ext = strtolower(array_pop($x));

		if($error == 4){
			$problem .= $upload_errors[$error]."<br>";
		}else{

			if($error != 0){
				$problem .= $upload_errors[$error]."<br>";
			}
			if(!in_array($ext,$expected_ext)){
				$problem .= "We do expect ".implode(', ',$expected_ext)." extentions only <br/>";
			}

			if($size > $expected_size){
				$problem .= "File Should be less than or equal to ".($expected_size/1024)."KB";
			}
		}


		$final_name = time()."_nhipp_39.".$ext;
		$path = $upload_dir."/".$final_name;

		if(empty($problem)){
			if(move_uploaded_file($tmp,$path)){
				return $final_name;
			}else{
				$problem .= "Unable to move file to upload directory";
			}
		}


		return false;
	}