ex05

Exercise 05: Harl 2.0

Objective:

This exercise introduces the concept of pointers to member functions in C++. Pointers to member functions allow you to call a member function on an instance of a class dynamically, which is useful for reducing the complexity of your code, especially when you have to call one of several functions based on some condition.

Key Concepts:

1. Pointers to Member Functions:

   • A pointer to a member function allows you to call member functions dynamically, avoiding the need for lengthy if/else or switch statements.
   • This mechanism provides a more elegant and scalable way to handle multiple functions based on some criteria, such as a string input representing different complaint levels.

2. Dynamic Function Calls:

   • Instead of using traditional control structures to determine which member function to call, an array of function pointers is used.
   • This array maps each possible input (e.g., "DEBUG", "INFO", "WARNING", "ERROR") to its corresponding member function.

3. Class Design:

   • The Harl class contains four member functions (debug(), info(), warning(), and error()) that represent different levels of complaints.
   • A public function complain(std::string level) uses the input level to determine which member function to call using the function pointer array.

Detailed Explanation:

1. Member Functions:

   • The Harl class contains four member functions: debug(), info(), warning(), and error().
   • Each function prints a message to the console, representing a different level of complaint.
   • The debug() function prints "DEBUG: This is a debug message."
   • The info() function prints "INFO: This is an info message."
   • The warning() function prints "WARNING: This is a warning message."
   • The error() function prints "ERROR: This is an error message."

2. Array of Function Pointers:

   • An array of pointers to member functions is declared and initialized within the complain function.
   • Each element of the array corresponds to one of the complaint levels and points to the respective member function.

3. Complain Function:

   • The complain function iterates through the array of complaint levels and compares each level to the input level.
   • When a match is found, the corresponding member function is called using the pointer to the member function.

Summary:

This exercise demonstrates how to use pointers to member functions in C++ to dynamically call member functions based on some criteria. By using an array of function pointers, you can avoid lengthy if/else or switch statements and provide a more elegant and scalable solution for handling multiple functions.