是（int）$ _ GET ['user_input']安全吗？

Question

Is it safe to assume that in

if (($i = (int)trim($_GET['user_input'])) != 0) {
    // do stuff with $i
}

$i can only ever be an integer?

---

Edit:

I now use:

if (ctype_digit($i = $_GET['user_input'])) {
    // do stuff with $i
}

Answer 1

So if your only question is if it's in any case a int, then is the answer :

Yes

But if the cast to int fails (e.g. input: 'a') $i is just 0

Example:

Input/ Output:

4       ->  4
-5      -> -5
"14"    -> 15
"a"     ->  0
"!"     ->  0
array() ->  0

Side Note:

If the value is an array trim fails and you get an error