Oppiskele Defining Custom Exceptions | Custom Exception Types

Why Use Custom Exceptions in C++

Custom exception types provide a way to make your error handling more descriptive and specific. Rather than relying solely on generic exceptions, you can create exception classes that clearly indicate what went wrong in your program. This is especially helpful in larger codebases or libraries, where you want to distinguish between different error conditions and handle them appropriately.

In C++, you typically define a custom exception by creating a class that inherits from std::exception. By overriding the what() method, you can provide a detailed error message that can be retrieved when the exception is caught.

InvalidAgeException.h

InvalidAgeException.cpp


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#ifndef INVALIDAGEEXCEPTION_H
#define INVALIDAGEEXCEPTION_H

#include <exception>
#include <string>

class InvalidAgeException : public std::exception {
public:
    explicit InvalidAgeException(const std::string& message)
        : msg_(message) {}

    virtual const char* what() const noexcept override {
        return msg_.c_str();
    }

private:
    std::string msg_;
};

#endif // INVALIDAGEEXCEPTION_H

Best Practices for Custom Exception Classes

When defining custom exception classes like InvalidAgeException, it is best practice to inherit from std::exception so your class integrates with standard exception handling mechanisms. Always override the what() method to provide a clear, informative error message. Store the message in a member variable to ensure it remains valid for the lifetime of the exception object.

Keep your exception classes lightweight and focused on describing the error;
Avoid unnecessary complexity;
Use meaningful, descriptive error messages;
Ensure your exception class is easy to use and maintain.

This approach makes your code easier to debug and maintain.

1. Which of the following is a key benefit of using custom exception types in C++?

2. Which method should you override when creating a custom exception class that inherits from `std::exception`? (Select all that apply.)

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Why Use Custom Exceptions in C++

InvalidAgeException.h

InvalidAgeException.cpp


              123456789101112131415161718192021
            
#ifndef INVALIDAGEEXCEPTION_H
#define INVALIDAGEEXCEPTION_H

#include <exception>
#include <string>

class InvalidAgeException : public std::exception {
public:
    explicit InvalidAgeException(const std::string& message)
        : msg_(message) {}

    virtual const char* what() const noexcept override {
        return msg_.c_str();
    }

private:
    std::string msg_;
};

#endif // INVALIDAGEEXCEPTION_H

Best Practices for Custom Exception Classes

Keep your exception classes lightweight and focused on describing the error;
Avoid unnecessary complexity;
Use meaningful, descriptive error messages;
Ensure your exception class is easy to use and maintain.

This approach makes your code easier to debug and maintain.

1. Which of the following is a key benefit of using custom exception types in C++?

2. Which method should you override when creating a custom exception class that inherits from `std::exception`? (Select all that apply.)

Oliko kaikki selvää?

Kiitos palautteestasi!

Osio 2. Luku 1

Defining Custom Exceptions

Why Use Custom Exceptions in C++

Best Practices for Custom Exception Classes

1. Which of the following is a key benefit of using custom exception types in C++?

2. Which method should you override when creating a custom exception class that inherits from std::exception? (Select all that apply.)

Awesome!

Defining Custom Exceptions

Why Use Custom Exceptions in C++

Best Practices for Custom Exception Classes

1. Which of the following is a key benefit of using custom exception types in C++?

2. Which method should you override when creating a custom exception class that inherits from std::exception? (Select all that apply.)

2. Which method should you override when creating a custom exception class that inherits from `std::exception`? (Select all that apply.)

2. Which method should you override when creating a custom exception class that inherits from `std::exception`? (Select all that apply.)