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C++ Quiz #145

Guards Closing During Unwinding

mediumExceptions

Each function owns a Guard that prints when it is built and when it is destroyed. inner() throws. What is printed?

📄 Code

1#include <iostream>
2#include <stdexcept>
3#include <string>
4 
5struct Guard {
6    std::string name;
7    Guard(const std::string& n) : name(n) { std::cout << "open " << name << "\n"; }
8    ~Guard() { std::cout << "close " << name << "\n"; }
9};
10 
11void inner() {
12    Guard g("inner");
13    throw std::runtime_error("fail");
14}
15 
16void outer() {
17    Guard g("outer");
18    inner();
19    std::cout << "after inner\n";
20}
21 
22int main() {
23    try {
24        outer();
25    } catch (const std::exception& e) {
26        std::cout << "caught " << e.what() << "\n";
27    }
28    return 0;
29}