Re: [Boost-bugs] [Boost C++ Libraries] #1856: minstd_rand returning different values in 1.35.0 than in 1.34.1

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #1856: minstd_rand returning different values in 1.35.0 than in 1.34.1
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-02-22 23:36:21

#1856: minstd_rand returning different values in 1.35.0 than in 1.34.1
----------------------------------------------------+-----------------------
  Reporter:  Greg Landrum <greg.landrum_at_[hidden]>  |       Owner:  no-maintainer
      Type:  Bugs                                   |      Status:  closed       
 Milestone:  Boost 1.36.0                           |   Component:  random       
   Version:  Boost 1.35.0                           |    Severity:  Problem      
Resolution:  invalid                                |    Keywords:               
----------------------------------------------------+-----------------------
Changes (by steven_watanabe):

  * status:  new => closed
  * resolution:  => invalid

Comment:

 The values returned by minstd_rand are the same for both
 versions.  The difference is in uniform_int.

 uniform_int didn't handle signed/unsigned issues correctly
 in 1.33.1.  Debugging this test case with 1.33.1 shows that during the
 second iteration (which prints 854 or 844), for the comparison on
 uniform_int.hpp line 97
 {{{
   if(result <= _range)
 }}}
 result is 9bad7746 and _range is 7fffffff.
 Since both arguments are signed, the comparison
 returns true, which is incorrect.

 So, I modified the test case to print out the actual values
 returned by uniform_int, and some of them are indeed negative.

 The current behavior is correct, so I'm marking this as invalid.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/1856#comment:1>
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