// RAII: Resource Acquisition Is Initialization
// - Tie resource management to object lifetime.
// - ifstream does it well.
// - Who frees p’s memory if an error is thrown?

#include <iostream>	// for cout, cerr
#include <fstream>	// for ifstream
#include <memory>	// for unique_ptr

using namespace std;

void bar() {
    ifstream in("/etc/resolv.conf");
    double *p = new double;
    // unique_ptr<double> p(new double);
    string s;
    if (getline(in, s) && s != "FIRST")
	throw "I am unhappy"s;		// oops--forgot to delete p
    cout << "The first line is " << s << '\n';

    delete p;
}

void foo() {		// Having foo() call bar() reminds the students
    bar();		// that exceptions propagate through function calls
}

int main() {
    try {
	foo();
    }
    catch (const string &msg) {
	cerr << "Caught an error: " << msg << "\n";
    }
    return 0;		// optional
}