Re: cout << vector<string>

From:

Maxim Yegorushkin <maxim.yegorushkin@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Mon, 10 Nov 2008 01:19:54 -0800 (PST)

Message-ID:

<b2fe2454-1f80-4c9b-9369-2d477fcdd5c9@z6g2000pre.googlegroups.com>

On Nov 7, 12:17 pm, Pete Becker <p...@versatilecoding.com> wrote:

On 2008-11-07 06:03:15 -0500, Maxim Yegorushkin
<maxim.yegorush...@gmail.com> said:

The example probably assumes there is an overloaded operator<<() for
std::ostream and std::vector<>, something like this:

    #include <ostream>
    #include <iterator>
    #include <algorithm>

    namespace std {

        template<class A1, class A2>
        ostream& operator<<(ostream& s, vector<A1, A2> const& v=

ec)

{
copy(vec.begin(), vec.end(), ostream_iterator<A=

1>(s, "

"));
            return s;
        }

    }

Which has undefined behavior. You can only add template specializations
to namespace std when they depend on user-defined types.

Formally true.

On practice it works just fine as long as One Definition Rule is not
violated.

--
Max