title: How to get the first n elements of a std::map
body: <p>Since there is no .resize() member function in C++ std::map I was wondering, how one can get a std::map with at most n elements.</p>
  
  <p>The obvious solution is to create a loop from 0 to n and use the nth iterator as the first parameter for std::erase().</p>
  
  <p>I was wondering if there is any solution that does not need the loop (at least not in my user code) and is more "the STL way to go".</p>