Unexpected PHP integer overflow on 64-bit systems

Asked Jul 18 '14 at 17:52

Active Jul 18 '14 at 17:52

Viewed 179 times

My code includes the following snippet:

public function query($query)
{
    static $seed = 0;
    $seed = max($seed + 1, (int)(microtime(true) * 10000));
    ...
}

This operation succeeds on my machine (i.e., $seed = 14057043101099). On both servers, however, it fails on the first attempt, assigning $seed = 1, after which it succeeds every time.

All three machines are PHP 5.3.X on CentOS 6.5 64-bit. I have tested and confirmed that they all return the correct response for 64-bit integers:

$ php -a

php > echo PHP_INT_MAX;
9223372036854775807

php > echo (int)(microtime(true) * 10000);
14057043101145

The following workaround solved the problem:

public function query($query)
{
    static $seed = 0;
    $seed = max($seed + 1, round((microtime(true) * 10000)));
    ...
}

I cannot find any explanation for this behavior. Ideas?

asked Jul 18 '14 at 17:52

vanwinter

could it be something with signed/unsigned?] – DTSCode Jul 18 '14 at 17:55
I doubt it. We are well within the 64-bit int range. – vanwinter Jul 19 '14 at 04:43
being on 64 bit software != 64 bit php. http://stackoverflow.com/a/864402/3784644 – DTSCode Jul 19 '14 at 05:20
@DTSCode Absolutely! That's why I included my PHP_INT_MAX test in the original post. – vanwinter Jul 19 '14 at 22:08
my bad didnt see that. edit: at the time that I wrote it. – DTSCode Jul 19 '14 at 22:23

Unexpected PHP integer overflow on 64-bit systems

0 Answers0