How to treat std::pair as two separate variables?

std::tie from the <tuple> header is what you want.

std::tie(it, b) = mymap.insert(std::make_pair(42, 1));

"magic" :)

Note: This is a C++11 feature.

In C++17, you can use structured bindings. So you don't have to declare the variables first:

auto [it, b] = mymap.insert(std::make_pair(42, 1));