Three Levels Deep

1#include <iostream>
2#include <stdexcept>
3 
4void level3(int n) {
5    std::cout << "level3 start\n";
6    if (n == 0) {
7        throw std::runtime_error("n is zero");
8    }
9    std::cout << "level3 end\n";
10}
11 
12void level2(int n) {
13    std::cout << "level2 start\n";
14    level3(n);
15    std::cout << "level2 end\n";
16}
17 
18void level1(int n) {
19    std::cout << "level1 start\n";
20    level2(n);
21    std::cout << "level1 end\n";
22}
23 
24int main() {
25    try {
26        level1(1);
27        level1(0);
28    } catch (const std::runtime_error& e) {
29        std::cout << "main caught: " << e.what() << "\n";
30    }
31    std::cout << "main end\n";
32    return 0;
33}