PHP mt_rand 每次都返回相同的数字

Question

random.php

$min=1;
$max=13031;
$ran_num = mt_rand($min,$max);
echo $ran_num;

This is working fine on my local host, but when I run it on my server, it always return the same number. not sure what is going on.

Update: I am running a wordpress site, and I put the random.php in the theme folder. I also have eaccelerator installed, this might be the issue, I am looking into it now

Answer 1

如果您的服务器 PHP 低于 4.2 - 您需要先调用mt_srand才能使用 mt_rand

Answer 2

By default modern PHP creates different number for mt_rand (it's uses libc random number generator), so the problem can be somewhere else.

This can likely to be caused by some caching, for example check the followings:

• clear your web browser caching (use private mode or use different browser),
• disable Varnish (if it's in use),
• check whether code is using memory caching like Memcached/Redis,
• this may be related to PHP cache accelerators (but less likely),
• restart your web server just in case (could be some extra caching module),
• make sure you're editing the right file and it was deployed properly,
• test it in the smallest possible PHP code.

Answer 3

Wordpress may use cache, and if you reload the page, it loads from cache, so you will see the same random number again and again. It has nothing to do with PHP version in this particular case - to fix this, it is needed to disable the wordpress cache.