system_error

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1. Catching a system error using try and catch

#include <iostream>
#include <system_error>

int main() {
    try {
        // Code that may throw a system error
    } catch (std::system_error& e) {
        std::cerr << "Error code: " << e.code() << '\n';
        std::cerr << "Message: " << e.what() << '\n';
    }

    return 0;
}

2. Getting the error code and message

std::error_code ec;
try {
   // Code that may throw a system error
} catch(...) {
   // The default constructor for std::error_code creates
   // an error code with value 0 and message "Success".
   ec = std::error_code(std::current_exception());
}

std::cout << "Error code: " << ec.value() << '\n';
std::cout << "Message: " << ec.message() << '\n';

3. Checking for a specific error code

std::error_code ec;
try {
   // Code that may throw a system error
} catch(...) {
   ec = std::error_code(std::current_exception());
}

if (ec == std::errc::invalid_argument) {
   std::cout << "Invalid argument\n";
}

4. Using std::make_error_code to create an error code

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::cout << "Error code: " << ec.value() << '\n';
std::cout << "Message: " << ec.message() << '\n';

5. Using std::error_category to get a human-readable description of the error

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::error_category& cat = ec.category();
std::string description = cat.message(ec.value());

std::cout << "Error description: " << description << '\n';

6. Using std::system_category to get the error category for system errors

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::error_category& cat = std::system_category();
std::string description = cat.message(ec.value());

std::cout << "Error description: " << description << '\n';

7. Using std::generic_category to get the error category for generic errors

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::error_category& cat = std::generic_category();
std::string description = cat.message(ec.value());

std::cout << "Error description: " << description << '\n';

8. Using std::io_category to get the error category for I/O errors

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::error_category& cat = std::io_category();
std::string description = cat.message(ec.value());

std::cout << "Error description: " << description << '\n';

9. Using std::network_category to get the error category for network errors

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::error_category& cat = std::network_category();
std::string description = cat.message(ec.value());

std::cout << "Error description: " << description << '\n';

10. Using std::system_error to create a system error

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::system_error e(ec);

std::cout << "Error code: " << e.code() << '\n';
std::cout << "Message: " << e.what() << '\n';

11. Using std::make_system_error to create a system error

std::error_code ec = std::make_error_code(std::errc::invalid_argument);

std::system_error e = std::make_system_error(ec);

std::cout << "Error code: " << e.code() << '\n';
std::cout << "Message: " << e.what() << '\n';

12. Using std::error_condition to create an error condition

std::error_condition ec = std::make_error_condition(std::errc::invalid_argument);

if (ec) {
    std::cout << "Error code: " << ec.value() << '\n';
    std::cout << "Message: " << ec.message() << '\n';
}

13. Using std::make_error_condition to create an error condition