rewrite access to collection to avoid “double” finding

Question

I have such code:

std::unordered_map futOrders;

auto i = futOrders.find(orderId);
if (i == futOrders.end()) {
    LimitOrd         


        

Answer 1

You can perform an emplace, and check the return value to know whether the item was inserted or not:

std::unordered_map futOrders;

auto i = futOrders.emplace(
           std::piecewise_construct, std::tie(orderId), std::make_tuple());
if (i.second) {
    LimitOrder& newOrder = i.first->second;
            // work
} else {
    LimitOrder& futOrder = i.first->second;
            // another work
}