I am currently maintaining a project written using Borland C++ Builder version 6 build 10.166 and boost version 1.32.

I found I had a reoccuring problem in my code whereby the output from lexical_cast<string>(any_double) was not at the precision I was expecting.  It started off OK, but after a while it changed.  I have tracked it down to some of my code which I simplified to that shown below.

The first cast, in the try block, works correctly with the output value d = 5.0 and no assert

The second cast, in the catch statement, returns a value of d = 5.00000013628211 and asserts.

With the assert removed, all subsequent calls to lexical_cast continue to give similar results.

try

{

  double d = boost::lexical_cast<double>(boost::lexical_cast<std::string>(5.0));

  assert(d == 5.0);

  throw std::runtime_error("Not enough points in peak");

}

catch (std::exception& e)

{

  double d = boost::lexical_cast<double>(boost::lexical_cast<std::string>(5.0));

  assert(d == 5.0);

}

I have searched the boost website for similar problems and have not found anything (doesn’t mean it’s not there, just I haven’t found it)

Any help, especially a solution or work around would be greatly appreciated.

NOTE at this time, due to the current state of the project, I would prefer not to have to upgrade to a newer version of the boost library.

Laurence Bunnage

Software Engineer

e-mail: Laurence.Bunnage@teraview.com

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