Manipulators That Leak Out of operator<<

1#include <iostream>
2#include <iomanip>
3using namespace std;
4 
5class Price {
6    double m_value;
7public:
8    Price(double value) : m_value(value) {}
9    friend ostream& operator<<(ostream& os, const Price& p);
10};
11 
12ostream& operator<<(ostream& os, const Price& p) {
13    os << setfill('.') << setw(8) << fixed << setprecision(2) << p.m_value;
14    return os;
15}
16 
17int main() {
18    Price p(3.5);
19    cout << p << endl;
20    cout << setw(6) << 42 << endl;
21    cout << 2.0 / 3 << endl;
22    cout << 7 << endl;
23    return 0;
24}