how to print out all elements in a std::stack or std::queue conveniently

Question

If I do not to want to create a new container in order to do so?

Answer 1

I've found solution which should work with all implementations (IMO) of std::stack, but unfortunately the stack must use std::vector instead of queue.

template
void printStack(const std::stack>& s)
{
    typedef typename std::stack::const_reference EntryTypeRef;
    typedef std::remove_reference_t EntryType;

    for(size_t i=0; i < s.size(); ++i)
    {
        EntryType* e = &s.top();
        cout << *(e-i) << endl;
    }
}

std::vector is dynamic array, so we can use pointer arytmetics.

The marked answer to the question assumes, that the stack has field named 'c', I have another solution which would work with std::stack implementation which has container as first field, but its name does not matter:

template
void printStack(const std::stack& s)
{
    typedef typename std::stack::container_type Container;

    const auto containerPtr = reinterpret_cast(&s);

    for(auto e : *containerPtr)
        cout << e << endl;
}