C++: Printing or cout a standard library container to console

Question

What's the C++ way to print or cout a C++ standard library container to the console, to view its contents?

On a separate note, why doesn't the C++ library actually overload the << operator for you? Any history behind it?

Answer 1

Overloading the operator<< for ostream is the way to go. Here's one possibility:

template <class container>
std::ostream& operator<<(std::ostream& os, const container& c)
{
    std::copy(c.begin(),
              c.end(),
              std::ostream_iterator<typename container::value_type>(os, " "));
    return os;
}

Then you can simply write:

std::cout << SomeContainer << std::endl;

Here are some other actually really nice solutions: Pretty-print C++ STL containers