Exception handling in C++ technology: How to define and throw error codes for custom exceptions?

C In exception handling, custom exceptions and error codes can provide more detailed error information. You can define an exception class derived from std::exception, including descriptive member variables and functions, and use the std::make_error_code() function to throw an exception containing an error code. After an exception is caught, the error message can be accessed from e.what() and the error code from e.code() for more efficient error handling and diagnosis.

Exception handling in C technology: Custom exceptions and error codes

In C, exception handling is a powerful mechanism that allows us to be elegant Handle error conditions gracefully, thereby improving code readability and maintainability. Defining and throwing custom exceptions, together with error codes, can provide more specific and useful error information, thereby helping us quickly diagnose and solve problems.

Define custom exceptions

In order to define custom exceptions, we need to create an exception class derived from std::exception. This class should contain member variables and functions that describe the error.

For example, we can define an exception class named MyException:

#include <stdexcept>
#include <string>

class MyException : public std::exception {
private:
    std::string message_;
public:
    MyException(const std::string& message) : message_(message) {}
    const char* what() const noexcept override { return message_.c_str(); }
};

Throw error code

When an exception is thrown, we also An error code can be included to provide additional information about the error. We can use the std::make_error_code() function to create an error code.

The following is an example of adding an error code to a MyException exception:

#include <system_error>

throw MyException(std::make_error_code(std::errc::invalid_argument).message());

Practical case

Consider the following code example:

try {
    // 可能会引发错误的代码
    ...
} catch (const MyException& e) {
    // 处理错误，并从 e.what() 访问错误消息
    std::cerr << "Error: " << e.what() << std::endl;
    // 还可以从 e.code() 访问错误码
    std::cerr << "Error code: " << e.code().value() << std::endl;
}

Caveats

• Make sure your custom exception class has a descriptive name and message to clearly communicate the error condition.
• Try to avoid using common error codes, such as std::errc::invalid_argument. Instead, define your own error codes to provide more specific error information.
• Where possible, include contextual information about the error that was raised to aid debugging.

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