cpp 01

The code you provided is an implementation of a simple Zombie class in C++, and it demonstrates how you can create and interact with instances of this class in different ways (by value, by pointer, and using temporary objects). Let's break it down and explain each part:

Code Overview:

1. The Zombie class:

class Zombie {
private:
    std::string _name; // Member variable to store the zombie's name

public:
    // Constructor to initialize a Zombie with a name
    Zombie(std::string name);
    
    // Destructor to handle cleanup when a Zombie is deleted
    ~Zombie();
    
    // Method to announce the Zombie
    void announce(void);
};

• The Zombie class has a private member variable _name to store the name of the zombie.
• It has:
  • A constructor to initialize a zombie's name.
  • A destructor to announce the zombie's death when it is destroyed.
  • An announce() method that outputs the zombie's name followed by a sound ("BraiiiiiiinnnzzzZ...").

main() function:

int main(void) {
  // Create Zombie class
  Zombie zombie = Zombie("Foo");
  zombie.announce();
  
  // It creates a zombie, names it, and returns it so you can use it outside of the function scope.
  Zombie *newZ = newZombie("newZombie");
  newZ->announce();
  
  // It creates a zombie, names it, and the zombie announces itself.
  randomChump("randomChump");
  
  // Zombie must be destroyed.
  delete newZ;
  
  // Uncomment below if you want to check memory leaks (only works on macOS or Unix-like systems).
  // system("leaks Zombie");
  return (0);
}

• Line 3:
  • Zombie zombie = Zombie("Foo"); creates a local zombie object named zombie. The constructor is called with the string "Foo", so the zombie's name is set to "Foo". The announce() method is then called on zombie, and the zombie announces itself as "Foo: BraiiiiiiinnnzzzZ...".
• Line 6:
  • Zombie *newZ = newZombie("newZombie"); calls the newZombie() function, which creates a dynamically allocated zombie (a pointer to a zombie) and names it "newZombie". The pointer newZ holds the memory address of the newly created zombie.
  • Then, the announce() method is called on newZ, which prints "newZombie: BraiiiiiiinnnzzzZ...".
• Line 9:
  • randomChump("randomChump"); calls the randomChump() function, which creates a temporary zombie named "randomChump". The announce() method is called, so "randomChump: BraiiiiiiinnnzzzZ..." is printed. This zombie is automatically destroyed after the function scope ends.
• Line 13:
  • delete newZ; deletes the dynamically allocated zombie (newZ). Since this zombie was created using new Zombie(), the delete keyword is necessary to free the allocated memory. The destructor is called when the zombie is deleted, so it announces "newZombie is dead." before the memory is freed.
• Line 15:
  • system("leaks Zombie"); is a system command that checks for memory leaks (only works on macOS or Unix-based systems). If there are any memory leaks, it will show them, though this line is commented out.

Functions:

newZombie():

Zombie *newZombie(std::string name) {
    return new Zombie(name);
}

• This function creates a dynamically allocated Zombie object using new and returns a pointer to it. The zombie's name is passed as a parameter, and the constructor is called to set its name.

randomChump():

void randomChump(std::string name) {
    Zombie tmp = Zombie(name);
    tmp.announce();
}

• This function creates a local zombie object named tmp (using automatic storage, meaning it’s not dynamically allocated). The announce() method is called on this zombie, and then the zombie is destroyed when the function scope ends. The destructor will be called automatically, and it will print that the zombie is dead.

Constructor and Destructor:

Constructor:

Zombie::Zombie(std::string name) {
    this->_name = name;
}

• The constructor takes a string parameter name and assigns it to the private member variable _name of the zombie.

Destructor:

Zombie::~Zombie() {
    std::cout << this->_name << " is dead." << std::endl;
}

• The destructor is called when a Zombie object is destroyed, whether it's a local object or one dynamically allocated with new. It prints a message like "ZombieName is dead." to indicate the zombie’s demise.

announce() method:

void Zombie::announce(void) {
    std::cout << this->_name << ": BraiiiiiiinnnzzzZ..." << std::endl;
}

• The announce() method outputs the name of the zombie followed by "BraiiiiiiinnnzzzZ...". This is the "signature" behavior of the zombie.

Key Points:

1. Local Zombies: Zombies created as local objects (like zombie and tmp) are automatically destroyed when they go out of scope, and their destructors are called.
2. Dynamically Allocated Zombies: Zombies created with newZombie() are dynamically allocated, so they need to be manually deleted using delete to avoid memory leaks.
3. Temporary Zombies: In randomChump(), a temporary zombie is created, and its destructor is called when the function ends, automatically announcing its death.

Conclusion:

This code demonstrates basic C++ object management, including dynamic memory allocation (new/delete), object constructors and destructors, and class method calls. The program creates and destroys zombies in various scopes (local, dynamic, and temporary), and it carefully manages memory to avoid leaks.