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C++ Quiz #151

Handler Order for Three Levels

mediumExceptions

DbError derives from AppError, which derives from std::runtime_error. Which handler order lets every exception reach the MOST specific handler that fits it?

📄 Code

1#include <iostream>
2#include <stdexcept>
3#include <string>
4 
5class AppError : public std::runtime_error {
6public:
7    using std::runtime_error::runtime_error;
8};
9 
10class DbError : public AppError {
11public:
12    using AppError::AppError;
13};
14 
15void run(int step) {
16    if (step == 1) {
17        throw DbError("connection lost");
18    }
19    if (step == 2) {
20        throw AppError("bad setting");
21    }
22    if (step == 3) {
23        throw std::runtime_error("disk full");
24    }
25    std::cout << "step " << step << " ok\n";
26}
27 
28int main() {
29    for (int step = 1; step <= 4; step++) {
30        try {
31            run(step);
32        } catch (const DbError& e) {
33            std::cout << "db: " << e.what() << "\n";
34        } catch (const AppError& e) {
35            std::cout << "app: " << e.what() << "\n";
36        } catch (const std::exception& e) {
37            std::cout << "std: " << e.what() << "\n";
38        }
39    }
40    return 0;
41}