[Boost-bugs] [Boost C++ Libraries] #12881: Reducing the precision integer division in VS 2015 and above

Subject: [Boost-bugs] [Boost C++ Libraries] #12881: Reducing the precision integer division in VS 2015 and above
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2017-03-01 15:03:46

#12881: Reducing the precision integer division in VS 2015 and above
------------------------------+----------------------------
 Reporter:  runc              |      Owner:  johnmaddock
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  multiprecision
  Version:  Boost 1.63.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+----------------------------
 The result of the following code is different in VS 2013 and VS
 2015:[[br]]VS 2013 output "6"[[br]]VS 2015 output "5.9999999..9977"[[br]]

 {{{
 #include <iostream>
 #include <boost/multiprecision/cpp_dec_float.hpp>

 int main()
 {
     boost::multiprecision::cpp_dec_float_50 num = 180;
     boost::multiprecision::cpp_dec_float_50 res = num / 30;
     std::cout.precision(100);
     std::cout << res;
     std::getchar();
     return 0;
 }
 }}}
 The difference is explained by the presence in the file
 "boost\multiprecision\detail\default_ops.hpp" 2 block of code with
 check
 {{{
 #if !BOOST_WORKAROUND(BOOST_MSVC, < 1900)
 ...
 #endif
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/12881>
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