redefine operator

#include <iostream>
#include <cstdlib>
#include <string>
#include <fstream>
#include <vector>
using namespace std;
class Chara {
public:
  string name;
  int HP;
  friend ostream &operator<<(ostream &, Chara);
  friend istream &operator>>(istream &, Chara &);
};
ostream &operator<<(ostream &out, Chara c) {
  out << c.name << " " << c.HP;
  return out;
}
istream &operator>>(istream &in, Chara &c) {
  in >> c.name >> c.HP;
  return in;
}
int main() {
  vector<Chara> ch;
  ifstream fin("chara.txt");
  if (!fin) {
    cerr << "指定したファイルが見つかりません" << endl;
    exit(1);
  }
  while (fin) {
    Chara c;
    fin >> c;
    if (c.name != "") ch.push_back(c);
  }
  fin.close();
  for (Chara c: ch) cout << c << endl;
  return 0;
}