[Boost-users] Re: Streaming boost::optional yields inconsistent output in gcc 3.2.3

Peter Dimov wrote:

Eelis van der Weegen wrote:

...

Hi,

I defined the following operator to stream optional<char>'s:

std::ostream & operator<< (std::ostream & os, boost::optional<char> const & op) { if (op) os << *op; else os << '_'; return os; }

Now, when I use:

boost::optional<char> a ('a'); std::cout << a;

'a' is printed like I expected. However, when I use:

std::ostream_iterator oi (std::cout); *oi = a;

'1' is printed and my operator is apparently ignored (I expected another 'a'). Is this a gcc (3.2.3) issue or a boost issue?

Neither. Your operator<< definition should be in namespace boost.

Thanks a lot! For some reason I hadn't thought of potential namespace lookup issues but of course it makes perfect sense.