C++ Unleashed: From Zero to Hero

Previous chapter: Standard Template Library (STL)

Go to Table of Contents

Error Handling and Exceptions

In C++, effective error handling is crucial for creating robust applications. This chapter will cover the concept of exceptions, how to use them for error handling, and best practices for managing errors in your code.

The Concept of Exceptions

Exceptions are events that occur during program execution that disrupt the normal flow of the program. They can be used to signal errors or unexpected conditions. Instead of returning error codes, C++ provides a more structured way to handle errors through exceptions.

Key Components of Exception Handling

1. Throwing Exceptions: When an error condition is detected, an exception can be thrown using the throw keyword.
2. Catching Exceptions: Exceptions are caught using try and catch blocks.
3. Handling Exceptions: Once an exception is caught, you can handle it appropriately, such as logging the error or providing a fallback mechanism.

Using try, catch, and throw

Throwing Exceptions

To throw an exception, use the throw keyword followed by an instance of an exception class. C++ provides several built-in exception classes, but you can also create custom exceptions.

Example:

#include <iostream>
#include <stdexcept>

void divide(int a, int b) {
    if (b == 0) {
        throw std::invalid_argument("Division by zero is not allowed.");
    }
    std::cout << "Result: " << a / b << std::endl;
}

int main() {
    try {
        divide(10, 0);
    } catch (const std::invalid_argument& e) {
        std::cerr << "Error: " << e.what() << std::endl; // Outputs: Error: Division by zero is not allowed.
    }

    return 0;
}

Catching Exceptions

The try block contains code that might throw an exception, while the catch block defines how to handle it. You can catch specific exceptions or use a general catch-all.

Example:

#include <iostream>
#include <stdexcept>

void mightGoWrong() {
    throw std::runtime_error("Something went wrong!");
}

int main() {
    try {
        mightGoWrong();
    } catch (const std::runtime_error& e) {
        std::cerr << "Caught an exception: " << e.what() << std::endl; // Outputs: Caught an exception: Something went wrong!
    }

    return 0;
}

Multiple Catch Blocks

You can have multiple catch blocks to handle different types of exceptions.

Example:

#include <iostream>
#include <stdexcept>

void testFunction() {
    throw std::out_of_range("Out of range error!");
}

int main() {
    try {
        testFunction();
    } catch (const std::out_of_range& e) {
        std::cerr << "Out of range: " << e.what() << std::endl;
    } catch (const std::exception& e) {
        std::cerr << "Standard exception: " << e.what() << std::endl;
    }

    return 0;
}

Best Practices for Error Handling

1. Use Exceptions for Exceptional Cases: Only use exceptions for situations that are truly exceptional. Avoid using them for regular control flow.
2. Provide Meaningful Error Messages: When throwing exceptions, ensure the message clearly describes the error.
3. Catch by Reference: Catch exceptions by reference to avoid slicing and to improve performance.
4. Clean Up Resources: Use RAII (Resource Acquisition Is Initialization) to manage resources, ensuring they are released even in the presence of exceptions.
5. Document Exception Behavior: Clearly document which functions may throw exceptions, so users of your code are aware of potential error conditions.

Summary

In this chapter, we explored error handling in C++ using exceptions. You learned how to throw, catch, and handle exceptions effectively, along with best practices for robust error management. Understanding and implementing proper error handling will enhance the reliability of your C++ applications and improve user experience.

In the next chapter, we will delve into using xmake to Build Projects, where you’ll learn how to set up and manage builds for your C++ projects.

Next chapter: Concurrency and Multithreading