Can I print STL map with cout instead of iterator loop - c++

Question

#include <string>
#include <iostream>
#include <map>
#include <utility>
using namespace std;
int main()
{
map<int, string> Employees;
// 1) Assignment using array index notation
Employees[5234] = "Mike C.";
Employees[3374] = "Charlie M.";
Employees[1923] = "David D.";
Employees[7582] = "John A.";
Employees[5328] = "Peter Q.";
cout << Employees;
cout << "Employees[3374]=" << Employees[3374] << endl << endl;
cout << "Map size: " << Employees.size() << endl;
/*for( map<int,string>::iterator ii=Employees.begin(); ii!=Employees.end(); ++ii)
{
cout << (*ii).first << ": " << (*ii).second << endl;
}*/
system("pause");
}
I would like to know what to add in order for me to print cout << Employees; instead of using iterator.Because I did see some code can directly print the map content with just the simple cout << Anythg.I wonder what has made the code work?

Answer 1

Nop, or at least the standard library doesn't provide a default implementation of operator << for container and std::ostream.
Check out https://github.com/louisdx/cxx-prettyprint or write your own implementation of operator<<(std::ostream &, const std::map<T1, T2> &).
Here is simple implemenation, for the sake of example:
#include <map>
#include <string>
#include <iostream>
template<typename T1, typename T2>
std::ostream &operator<<(std::ostream &stream, const std::map<T1, T2>& map)
{
for (typename std::map<T1, T2>::const_iterator it = map.begin();
it != map.end();
++it)
{
stream << (*it).first << " --> " << (*it).second << std::endl;
}
return stream;
}
int main(int, char **)
{
std::map<std::string, int> bla;
bla["one"] = 1;
bla["two"] = 2;
std::cout << bla << std::endl;
return (0);
}