#include <iostream>
#include <map>
using namespace std;
map<int, string> d = {
{1, "A"}, {2, "B"}
};
//since C++17
auto value3 = d.try_emplace(3, "-");
//(*value3.first).second is "-"
bool exist3 = d.contains(3);
//exist3 is 1
cout << "exist3 is " << exist3 << endl;
cout << "value3 is '" << (*value3.first).second << "'"