A Family of Errors, Caught in Order

1#include <iostream>
2#include <stdexcept>
3#include <string>
4 
5class SensorError : public std::runtime_error {
6public:
7    explicit SensorError(const std::string& m) : std::runtime_error(m) {}
8};
9 
10class Disconnected : public SensorError {
11public:
12    Disconnected() : SensorError("sensor disconnected") {}
13};
14 
15class OutOfRange : public SensorError {
16public:
17    OutOfRange() : SensorError("reading out of range") {}
18};
19 
20int read(int sample) {
21    if (sample < 0) {
22        throw Disconnected();
23    }
24    if (sample > 100) {
25        throw OutOfRange();
26    }
27    return sample;
28}
29 
30int main() {
31    int samples[] = {20, -1, 150, 99};
32    for (int sample : samples) {
33        try {
34            int value = read(sample);
35            std::cout << "reading " << value << "\n";
36        } catch (const Disconnected& e) {
37            std::cout << "reconnect: " << e.what() << "\n";
38        } catch (const SensorError& e) {
39            std::cout << "sensor: " << e.what() << "\n";
40        }
41    }
42    return 0;
43}