从队列中删除第一个元素？

Question

I have a queue. If it exceeds X size, when I push an element I want to remove the first element of the queue. (the last element that would get popped and the first element pushed in)

void ClientPlayerManager::queueTableMessage( const std::string& playerName, const std::string& message )
{
    m_tableQ.push(std::make_pair(playerName,message));

    if(m_tableQ.size() > m_maxTableMessages)
    {
        //m_tableQ.pop_back(); does not exist
    }
}

Is there a way to do this with a std queue?

Thanks

Answer 1

You can use a std::deque instead of a std::queue , which supports push_front , push_back , pop_front , and pop_back . This also allows for random access throughout, but you can just ignore that and treat the deque like a double-ended queue. (In fact, deque is short for double-ended queue).

Hope this helps!

Answer 2

If you want to remove an element from the opposite end from what pop does, just skip pushing it in the first place:

if(m_tableQ.size() < m_maxTableMessages) {
    m_tableQ.push(std::make_pair(playerName,message));
}

Answer 3

Here is the another way to do it. Uses STL based queue implementation.