C++ Tutorial 10
I’m finally covering Object Oriented Programming with C++! I cover classes, objects, public, private, protected, constructors, deconstructors, pointer operator, dot operator, getters, setters, super classes, inheritance, calling super class functions, overwriting functions, and much more.
In the problem with this tutorial we will try to model a battle between the Hulk and Thor to the death. All of the code follows down below.
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Code & Transcript
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// ---------- INTRO TO CLASSES & INHERITANCE ---------- #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <sys/types.h> #include <dirent.h> #include <sys/stat.h> class Animal{ // Private variables are only available to methods // in the class private: std::string name; double height; double weight; // Static variables share the same value for all // objects of the Animal class static int numOfAnimals; // Public fields and methods can be accessed by // anything with access to the object public: std::string GetName(){return name;} // Because we don't know what an objects name is // because the class is created before the object // we can refer to all objects using this // The pointer operator is used to access an // objects fields and methods void SetName(std::string name){this->name = name;} double GetHeight(){return height;} void SetHeight(double height){this->height = height;} double GetWeight(){return weight;} void SetWeight(double weight){this->weight = weight;} // You can declare function prototypes void SetAll(std::string, double, double); // A constructor is called each time an object is created Animal(std::string, double, double); // Create an overloaded constructor for when no data is passed Animal(); // A deconstructor is called automatically when an object // is deleted or is no longer used // The default is fine, but you should create custom ones // when you must release memory, or resources ~Animal(); // Static methods can only access static fields static int GetNumOfAnimals(){return numOfAnimals;} // Created to be overwritten void ToString(); }; // Refer to class fields and methods with :: int Animal::numOfAnimals = 0; // Define the prototype method void Animal::SetAll(std::string name, double height, double weight){ this->name = name; this->weight = weight; this->height = height; Animal::numOfAnimals++; } // Define the constructor Animal::Animal(std::string name, double height, double weight){ this->name = name; this->weight = weight; this->height = height; Animal::numOfAnimals++; } Animal::Animal(){ this->name = ""; this->weight = 0; this->height = 0; Animal::numOfAnimals++; } Animal::~Animal(){ std::cout << "Animal " << this -> name << " destroyed\n"; } void Animal::ToString(){ std::cout << this -> name << " is " << this -> height << " cms tall and " << this -> weight << " kgs in weight\n"; } // Through inheritance a class inherits all fields and methods // defined by the super, or inherited from class class Dog: public Animal{ private: std::string sound = "Wooof"; public: // You can access to the private field name // by calling GetName() void MakeSound(){ std::cout << "The dog " << this->GetName() << " says " << this->sound << "\n"; } // The Dogs constructor Dog(std::string, double, double, std::string); // The default constructor calls Animals default // constructor Dog(): Animal(){}; // Overwrite ToString void ToString(); }; // Calls the superclasses constructor to handle // initalization Dog::Dog(std::string name, double height, double weight, std::string sound) : Animal(name, height, weight){ this -> sound = sound; } // Overwrite ToString void Dog::ToString(){ // Because the attributes were private in Animal they must be retrieved // by called the get methods std::cout << this -> GetName() << " is " << this -> GetHeight() << " cms tall, " << this -> GetWeight() << " kgs in weight and says " << this -> sound << "\n"; } int main() { // Create object without setting values in constructor Animal fred; fred.SetHeight(33); fred.SetWeight(10); fred.SetName("Fred"); // Get the values for the Animal fred.ToString(); fred.SetAll("Fred", 34, 12); fred.ToString(); // Setting values with constructor Animal tom("Tom", 36, 15); tom.ToString(); // Demonstrate inherited Dog class Dog spot("Spot", 38, 16, "Wooof"); // See different output from overwritten ToString() spot.ToString(); // Call static methods by using the class name to // show the total Animals created std::cout << "Number of Animals " << Animal::GetNumOfAnimals() << "\n"; return 0; } // ---------- END INTRO TO CLASSES & INHERITANCE ---------- // ---------- PROBLEM WARRIORS BATTLE TILL DEATH ---------- // Make this /* Thor attacks Hulk and deals 12 damage Hulk is down to 28 health Hulk attacks Thor and deals 3 damage Thor is down to 37 health Thor attacks Hulk and deals 14 damage Hulk is down to 14 health Hulk attacks Thor and deals 0 damage Thor is down to 37 health Thor attacks Hulk and deals 14 damage Hulk is down to 0 health Hulk has Died and Thor is Victorious Game Over */ #include <cstdlib> #include <iostream> #include <string> #include <vector> #include <ctime> #include <numeric> #include <math.h> class Warrior{ private: int attkMax; int blockMax; public: std::string name; int health; Warrior(std::string name, int health, int attkMax, int blockMax){ this->name = name; this->health = health; this->attkMax = attkMax; this->blockMax = blockMax; } // The attack and block amount will be random int Attack(){ return std::rand() % this->attkMax; } int Block(){ return std::rand() % this->blockMax; } }; class Battle{ public: // We pass warriors into the function by reference so we can // track continued damage to each // We continue to loop having each warrior take turns attacking // until a warriors health < 0 static void StartFight(Warrior& warrior1, Warrior& warrior2){ while(true){ if(Battle::GetAttackResult(warrior1, warrior2).compare("Game Over") == 0){ std::cout << "Game Over\n"; break; } if(Battle::GetAttackResult(warrior2, warrior1).compare("Game Over") == 0){ std::cout << "Game Over\n"; break; } } } static std::string GetAttackResult(Warrior& warriorA, Warrior& warriorB){ // Get random attack & block amounts and calculate damage int warriorAAttkAmt = warriorA.Attack(); int warriorBBlockAmt = warriorB.Block(); int damage2WarriorB = ceil(warriorAAttkAmt - warriorBBlockAmt); // Change health total if > 0 and output changes damage2WarriorB = (damage2WarriorB <= 0) ? 0 : damage2WarriorB; warriorB.health = warriorB.health - damage2WarriorB; printf("%s attacks %s and deals %d damage\n", warriorA.name.c_str(), warriorB.name.c_str(), damage2WarriorB); printf("%s is down to %d health\n", warriorB.name.c_str(), warriorB.health); // Once health < 0 end game by passing back Game Over if(warriorB.health <= 0){ printf("%s has Died and %s is Victorious\n", warriorB.name.c_str(), warriorA.name.c_str()); return "Game Over"; } else { return "Fight Again"; } } }; int main() { // Seed the random number generator srand(time(NULL)); // Create warriors Warrior tom("Thor", 100, 35, 15); Warrior sam("Hulk", 125, 25, 10); // Create battle and have it run on its own till completion Battle::StartFight(tom, sam); return 0; } // ---------- END PROBLEM WARRIORS BATTLE TILL DEATH ---------- |
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