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Bug #49701 rand always returns min value
Submitted: 2009-09-28 17:31 UTC Modified: 2009-09-29 15:23 UTC
From: applezinc at gmail dot com Assigned:
Status: Not a bug Package: Math related
PHP Version: 5.2.11 OS: slackware linux 12.2
Private report: No CVE-ID: None
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 [2009-09-28 17:31 UTC] applezinc at gmail dot com 
Description:
------------
getrandmax is 2^31.

if you put in a number for max greater than that (as the documentation says you can), the function always returns the min.

mt_rand is the same.

Reproduce code:
---------------
echo rand(1,4294967294);
echo "\n";
echo getrandmax();
echo "\n";


Expected result:
----------------
random number between 1 and 4294967294.

Actual result:
--------------
1

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 [2009-09-28 19:21 UTC] sjoerd@php.net 
Thank you for your bug report.

The techical reason this works like this is as follows: rand() takes two integers. When you specify a number bigger than 2^31, it is cast to float. When it is passed to rand(), it is cast to an int. The number 4294967294 then becomes -2.
 [2009-09-29 12:41 UTC] jani@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

.
 [2009-09-29 15:23 UTC] applezinc at gmail dot com 
No its not bogus. You told me to refer to the documentation, well here it is:

" If you require a range larger than 32768, specifying min  and max  will allow you to create a range larger than this, or consider using mt_rand() instead."


Your assumption that it is bogus is based upon what? that "int" is 16 bits?  int is defined as whatever register size the microprocessor can handle and it varies. 

I understand exactly what the prior poster said. I've been an embedded software engineer for 15 years.  However that's NOT what the documentation says.  So one of them is wrong.
 
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