[Boost-users] Bug in lexical_cast<> with doubles

From: Leon Raj (Leon.Raj_at_[hidden])
Date: 2004-07-27 23:21:23

I think I've found a bug in the boost::lexical_cast<>
library (v1.31.0) on WinXP SP1, MSVC 6.0 (sp5) and 
MSVC.NET 2003.

--- Start code snippet ---

#include <boost/lexical_cast.hpp>
#include <iostream>

int main( int argc, char* argv[] )
{
    double dMax = = std::numeric_limits< double >::max();
    // On a Win32 x86 system, dMax is now 1.7976931348623157e+308

    // This is successful and strMax is "1.797693134862316e+308"
    std::string strMax = boost::lexical_cast< std::string >( dMax );

    try
    {
        double newDMax = boost::lexical_cast< double >( strMax );
        std::cout << "Successfuly" << std::endl;
    }
    catch ( boost::bad_lexical_cast& )
    {
        std::cout << "Failed to cast" << std::endl;
    }

    // On a Win32 x86 system, this always fails,
    // because (I think) strMax overflows a double,
    // because 1.7976931348623157e+308 is *rounded UP* 
    // to      1.797693134862316e+308, which cannot be
    // represented by a double
}

--- End code snippet ---

----------------------------------------------------- 
Leon Raj 
Senior Engineer 
Invetech Pty. Ltd. 
Phone: [phone] (Switchboard) 
       [phone] (DDI) 
leon.raj_at_[hidden] 

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