<?php

$data = "10/01/2016";
function beforeSaveData($data){
    $data = explode("/", $data);
    $novaData = $data[2] . "-" . $data[1] . "-" . $data[0];
    return $novaData;	
}
$novaData = beforeSaveData($data);
echo $novaData;
// your code goes here