比较两个浮点值-不相同

Question

I´ve a strange problem and I hope you can help me.

I´ve two values at the beginning:

var_dump($order_sum);
var_dump($orders_obj->getOrders_preisliste_sum ());
var_dump($order_sum != $orders_obj->getOrders_preisliste_sum ());

Result:

float(49.7) 
string(7) "49.7000" 
bool(true)

Here all is okay, but why is that way also "true" if I compare them?

var_dump($order_sum);
var_dump(floatval($orders_obj->getOrders_preisliste_sum ()));
var_dump($order_sum != floatval($orders_obj->getOrders_preisliste_sum ()));

Result:

float(49.7) 
float(49.7) 
bool(true) <---

In my opinion it should be the same, but here PHP displays it as a different.

Answer 1

You could use bccomp function (bcmath extension) to compare your float values : http://www.php.net/manual/en/function.bccomp.php . Your values are actually not equals because of floating point precision as Adam just mentioned.