[Boost-users] Re: Two issues with lexical_cast

From: Yuval Ronen (ronen_yuval_at_[hidden])
Date: 2005-01-19 01:53:18

> For 2, It seems more like a problem with stringstream - I think
> lexical_cast does:
> 
> stringstream ss;
> ss << input;
> ss >> output;
> return output;

Not quite. In lexical_cast there's a code to specifically *not* ignore 
leading whitespace - look for for the line 
'stream.unsetf(std::ios::skipws)'. It also contains a code to 
specifically *ignore* trailing whitespace (but not other characters) - 
look for 'stream >> std::ws'. So this was done intentionally, even 
though mistakenly in my opinion.

My version of 'lexical_cast<T, string>' looks like (I hope I remember 
correctly):

template <typename T>
T convert_from_string(const string &str)
{
     T val;
     istringstream iss(str);
     iss >> noskipws >> val;
     if (iss.fail() || !iss.eof())
         throw ...;
     return val;
}

and it works fine. No problems with the stringstream.