o que tal este:
Código PHP:
function validar_form($form_vars)
{
// test that each variable has a value
foreach ($form_vars as $key => $value)
{
$key=htmlspecialchars($key);
if (!isset($key) || ($value == ""))
return false;
}
return true;
}
// Comprobamos los campos del form
if(!validar_form($HTTP_POST_VARS) ){
header ("Location: ?error=0");
exit;
}