Use a pointer to directly manipulate elements in an STL map

pointer_to_mapped.cpp

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

struct S{
	int data;
	float f;
	S(int d, float x): data(d), f(x) {}
	S(): data(0), f(0) {}
};

int main() {
	// your code goes here
	std::map<int, S> m;
	m.emplace(1, S(2, 3));
	m.emplace(3, S(4, 5));
	S *s = &m.at(3);
	s->f = 6;
	cout << m[3].f << endl;
	return 0;
}