std::pair用法

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

int main () {
  pair <string,double> product1 ("tomatoes",3.25);
  pair <string,double> product2;
  pair <string,double> product3;

  product2.first = "lightbulbs";     // type of first is string
  product2.second = 0.99;            // type of second is double

  product3 = make_pair ("shoes",20.0);

  cout << "The price of " << product1.first << " is $" << product1.second << "\n";
  cout << "The price of " << product2.first << " is $" << product2.second << "\n";
  cout << "The price of " << product3.first << " is $" << product3.second << "\n";
  return 0;
}