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POWorkaround for suhosin.mt_srand.ignore to consistently shuffle an array in PHP?
 

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  1. POWorkaround for suhosin.mt_srand.ignore to consistently shuffle an array in PHP?
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    <p>I have a PHP script which needs to randomise an array with consistent results, so it can present the first few items to the user and they can then pull in more results from the same shuffled set if they want to.</p> <p>What I'm currently using is this (based on the Fisher Yates algorithm I believe):</p> <pre><code>function shuffle(&amp;$array, $seed) { mt_srand($seed); for ($a=count($array)-1; $a&gt;0; $a--) { $b = mt_rand(0, $a); $temp = $array[$a]; $array[$a] = $array[$b]; $array[$b] = $temp; } } </code></pre> <p>Which works fine on my local installation, but the server it needs to run on has Suhosin installed, which overrides mt_srand, meaning the seed is ignored, the array is just randomly shuffled and the user gets duplicate results.</p> <p>Everything I've found on Google suggests I need to disable suhosin.mt_srand.ignore (and suhosin.srand.ignore, not sure if the latter is relevant though) so I put the following in .htaccess:</p> <pre><code>php_flag suhosin.mt_srand.ignore Off php_flag suhosin.srand.ignore Off </code></pre> <p>I have no access to php.ini on this server so AFAIK that's the only way I can do it. The problem is that has no effect - phpinfo() still shows both settings as On, whereas I can change other Suhosin settings using .htaccess no problem.</p> <p>So I suppose what I'm looking for is either a way to actually disable suhosin.mt_srand.ignore (or a reason why it isn't working), or a workaround to seed a random number generator from within PHP. Or will I just have to implement another RNG myself?</p> <p>Any help would be much appreciated. Thanks!</p>
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    1. COCache the resulting array somewhere, don't recreate it every request...
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    2. COSeems like that'd introduce a lot of issues for something that should be fairly simple though. By its nature it'd need to be reshuffled a lot (it's based on a search, each time the user searches it's reshuffled) and each shuffle would probably only be used 2 or 3 times max. It's a heavily used part of the site, so I'd be caching a *lot* of different shuffled versions of different result arrays for different users, probably in many cases the same results shuffled differently, and then I'd need to deal with storage and how long to retain each array and all that.
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    3. COIs it really a requirement, that _every_ user _must_ see a _completely_ different version, or can't you just use one shuffled set for multiple users?
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