Int casting gives wrong number on WAMP

Question

I have some legacy code on a Windows machine running PHP 5.6 that we will be dismissing but I need to do some migrations from.

I have trivial bit of code that is quite mistifying to me. I've simplified it for this question, but the behavior is the same.

$a = "3109584483";
$b = (int) $a;
var_dump($a);
var_dump($b);

And this is the output:

string(10) "3109584483"
int(2147483647)

I have looked at all the similar questions about this, but they all mention

• Casting a float (not my case)
• Getting the result in a non-10 base (I tried converting 2147483647 from and to common bases like HEX, OCT and BIN, but I can't seem to find a match that would justify the result)

What is the reason of this wrong casting? Thanks in advance for your help!