Re: [Boost-users] Is this a known bug in lexical_cast<double> ?

Subject: Re: [Boost-users] Is this a known bug in lexical_cast<double> ?
From: Jeff Flinn (jeffrey.flinn_at_[hidden])
Date: 2015-07-15 18:35:39

On 7/13/15 1:26 PM, TILLMAN, MICHAEL D9 wrote:
> We're using boost 1.51. Management is reluctant to upgrade because the
> software is for manned space flight and our current boost version has
> been stable.
>
> Wanted to see if there was a known bug with boost::lexical_cast<double>.
> We're seeing failures on what appear to be valid float strings. When we
> catch the exception, and simply do a second cast on the same string, the
> cast succeeds. The Code fragment:
>
>    try { dVal = boost::lexical_cast<double>(theValue); }
>
>    catch(boost::bad_lexical_cast &eX)
>
>    {
>
>      ... more code ...
>
>      firstAttemptFailed = true;
>
>    }
>
>    // If the first cast succeeded, don't bother to attempt it again.
>
>    if(firstAttemptFailed == true)
>
>    {
>
>      // Let the API throw the actual exception if the second attempt
> also fails.
>
>      dVal = boost::lexical_cast<double>(theValue);
>
>    }
>
> The string sequence this fails on is:
>
> ...
>
> ...
>
> "7104",
>
> "0.416666699999999999983",
>
> "0.22222224",
>
> "4.08233160000000000001",
>
> "1.81436960000000000002",
>
> ...
>
> It fails on the last string, "1.81.....", in the actual program, but
> when compiled into a simple test program, it succeeds.
>
> If there is a known bug, we may be able to get a Boost upgrade installed.

I don't know whether there are known bugs in lexical_cast, but I'd be 
more suspicious of theValue's actual value. What is it's type, lifetime, 
etc.

Jeff