How to define the exception class in C++ function exception handling?

Exception class defined in C: A new class needs to be derived from std::exception and override the what virtual function to provide exception messages; as shown in the example, the MyException class overrides what to return exception messages. In the actual case, the divide function throws a std::runtime_error exception, and the main function captures and prints the exception message.

Exception class definition in C function exception handling

In C, the exception class is used to handle function exceptions. To define an exception class, derive a new class from the std::exception class and override the what virtual function to provide the exception message.

The following is an example of defining an exception class:

#include <exception>

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

private:
  std::string message_;
};

In this example, the MyException class derives from the std::exception class, and Rewritten the what function to return an exception message. The message can be set in the constructor.

Practical case

The following is an example of a function that uses the exception class:

#include <exception>
#include <iostream>

void divide(int numerator, int denominator) {
  if (denominator == 0) {
    throw std::runtime_error("Cannot divide by zero");
  }
  std::cout << "Result: " << numerator / denominator << std::endl;
}

int main() {
  try {
    divide(10, 0);  // 抛出异常
  } catch (const std::exception& e) {  // 捕获异常
    std::cerr << "Error: " << e.what() << std::endl;
  }
  return 0;
}

In the above example, the divide function operates when the divisor is zero. Throws a std::runtime_error exception. The main function uses the try-catch block to catch exceptions and print the exception message.

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