How to use C++11 range based for loop correctly

Without deep understanding of C++11 range based for loop, it is easy to make stupid mistakes which is hard to understand reason by reading long and complex compiler error message. Here I list what is the right and wrong format to use C++11 range based for loop.

#include <iostream>
#include <map>
#include <string>
using namespace std;

int main()

{
  map<int, string> mapStudent;

  mapStudent.insert(pair<int, string>(1, "student_one"));

  mapStudent.insert(pair<int, string>(2, "student_two"));

  mapStudent.insert(pair<int, string>(3, "student_three"));

  map<int, string>::iterator iter;

  // Correct iterator usage before C++11
  for(iter = mapStudent.begin(); iter != mapStudent.end(); iter++)
  {
    cout << iter->first << " " << iter->second << endl;
  }
  
  // Wrong range based for loop usage, mix up iterator and range based for loop element
  //for (iter : mapStudent) {
  //  cout << iter->first << " " << iter->second << endl;
  //}






  
// Correct range based for loop usage, auto deduct element type
  for (auto &elem : mapStudent) {
    cout << elem.first << " " << elem.second << endl;
  }
// Correct range based for loop usage, explicitly tell the compiler the element type
  for (pair<int, string> elem : mapStudent) {
    cout << elem.first << " " << elem.second << endl;
  }
}



references:
http://www.kuqin.com/cpluspluslib/20071231/3265.html
http://en.cppreference.com/w/cpp/language/range-for