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 use this overload of insert instead:

std::pair insert( const value_type& value );

Example:

std::unordered_map m { {0, "A"}, {1, "B"}, {2, "C"} };

int orderId = 1;
// attempt to insert with key you have and default constructed value type
auto p = m.insert( std::make_pair(orderId, std::string()) );

if (p.second) {
    // the element was inserted
} else {
    // the element was not inserted
    std::cout << p.first->second;  // will print "B"
}

In both cases, p.first is the iterator to the element you search for (or just got inserted).