gcc内置的for each

#include <stdio.h>
#include <string>
#include <vector>
#include <map>

int main(int argc, char **argv)
{
	std::vector<int> myint;
	std::map<int,int> mymap;
	
	for(int i=0;i<12;i++)
	{
		myint.push_back(i);
		mymap[i]=i;
	}
	
	for(std::pair<const int,int> &x : mymap)
	{
		x.second=2*x.second;
	}
		
	for (auto &x : myint)
	{
	   x=2*x;
	}
	
	for (auto x : myint)
	{
	   printf("%d\n",x);
	}
	
	for(std::pair<const int,int> &x : mymap)
	{
		printf("%d	%d\n",x.first,x.second);
	}
	return 0;
}