Re: [Boost-users] [lexical_cast] lexical_cast<int>("1e4") == 1

From: Johan Råde (rade_at_[hidden])
Date: 2007-03-19 08:19:01

Paul Giaccone wrote:
> n.torrey.pines_at_[hidden] wrote:
>> lexical_cast<int>("1e4") == 1 // because of the way streams work of course
>>
>> I think that in the interests of robustness, and unless a better
>> solution can be found, lexical_cast<> should be secialized for some
>> types.
>>   
> 
> Interesting... I had exactly the same issue in MEL the other day. The 
> obvious workaround is to cast the string to a float before casting it to 
> an int, but it would be nice if lexical_cast<int> recognised 
> floating-point numbers in scientific notation.

C++ iostreams do not support integers in scientific notation.
There may be good reasons for that:

1.2345    is not an integer
1.2345e4  is an integer
1.2345e3  is not an integer

That makes the task of parsing integers in scientific notation a bit tricky.

--Johan