Suppose you are creating a fantasy role-playing game. In this game we have four different types of Creatures: Humans, Cyberdemons, Balrogs, and elves. To represent one of these Creatures we might define a Creature class as follows: class Creature { private: int type; // 0 Human, 1 Cyberdemon, 2 Balrog, 3 elf int strength; // how much damage this Creature inflicts int hitpoints; // how much damage this Creature can sustain string getSpecies() const; // returns the type of the species static constexpr double DEMONIC_ATTACK_PROBABILITY = 0.25; static const int DEMONIC_BONUS_DAMAGE = 50; static constexpr double MAGICAL_ATTACK_PROBABILITY = 0.5; static constexpr double MAGICAL_ATTACK_MULTIPLIER = 2.0; static const int DEFAULT_STRENGTH = 10
OOPs
In today's technology-driven world, computer programming skills are in high demand. The object-oriented programming (OOP) approach is very much useful while designing and maintaining software programs. Object-oriented programming (OOP) is a basic programming paradigm that almost every developer has used at some stage in their career.
Constructor
The easiest way to think of a constructor in object-oriented programming (OOP) languages is:
Suppose you are creating a fantasy role-playing game. In this game we have four different types of Creatures: Humans, Cyberdemons, Balrogs, and elves. To represent one of these Creatures we might define a Creature class as follows:
class Creature {
private:
int type; // 0 Human, 1 Cyberdemon, 2 Balrog, 3 elf
int strength; // how much damage this Creature inflicts
int hitpoints; // how much damage this Creature can sustain
string getSpecies() const; // returns the type of the species
static constexpr double DEMONIC_ATTACK_PROBABILITY = 0.25;
static const int DEMONIC_BONUS_DAMAGE = 50;
static constexpr double MAGICAL_ATTACK_PROBABILITY = 0.5;
static constexpr double MAGICAL_ATTACK_MULTIPLIER = 2.0;
static const int DEFAULT_STRENGTH = 10;
static const int DEFAULT_HITPOINTS = 10;
public:
Creature(); // initialize to Human, 10 strength, 10 hitpoints
Creature(int newType, int newStrength, int newHitpoints);
int getDamage() const; // returns the amount of damage this Creature
// inflicts in one round of combat
// also include appropriate accessors and mutators
};
Note: I realize we have not covered constexpr. For now, it is fine to just know that data members of type "double" cannot be const, so we use constexpr instead.
Here is an implementation of the getSpecies() function:
string Creature::getSpecies() const {
switch (type) {
case 0: return "Human";
case 1: return "Cyberdemon";
case 2: return "Balrog";
case 3: return "Elf";
}
return "unknown";
}
The getDamage() function outputs and returns the damage this Creature can inflict in one round of combat. The rules for determining the damage are as follows:
- Every Creature inflicts damage that is a random number r, where 0 < r <= strength.
- Demons have a DEMONIC_ATTACK_PROBABILITY (initially set to 25%) chance of inflicting a demonic attack which is an additional DEMONIC_BONUS_DAMAGE (initially set to 50) damage points. Balrogs and Cyberdemons are Demons.
- With a MAGICAL_ATTACK_PROBABILITY (initially set to 50%) chance, elves inflict a magical attack that multiplies the normal amount of damage by MAGICAL_ATTACK_MULTIPLIER (initially set to 2).
- Balrogs are very fast, so they get to attack twice
An implementation of getDamage() is given below:
int Creature::getDamage() const {
int damage;
// All Creatures inflict damage which is a random number up to their strength
damage = (rand() % strength) + 1;
cout << getSpecies() << " attacks for " << damage << " points!" << endl;
// Demons can inflict bonus damage of DEMONIC_BONUS_DAMAGE with a DEMONIC_ATTACK_PROBABILITY chance
if (type == 2 || type == 1){
if (rand() % 100 * 0.01 < DEMONIC_ATTACK_PROBABILITY) {
damage = damage + DEMONIC_BONUS_DAMAGE;
cout << "Demonic attack inflicts " << DEMONIC_BONUS_DAMAGE << " additional damage points!" << endl;
}
}
// Elves inflict multiplied magical damage with a MAGICAL_ATTACK_PROBABILITY chance
if (type == 3) {
if (rand() % 100 * 0.01 < MAGICAL_ATTACK_PROBABILITY) {
cout << "Magical attack inflicts " << damage << " additional damage points!" << endl;
damage *= MAGICAL_ATTACK_MULTIPLIER;
}
}
// Balrogs are so fast they get to attack twice
if (type == 2) {
int damage2 = (rand() % strength) + 1;
cout << "Balrog speed attack inflicts " << damage2 << " additional damage points!" << endl;
damage += damage2;
}
return damage;
}
One problem with this implementation is that it is unwieldy to add new Creatures. Rewrite the class to use inheritance, which will eliminate the need for the variable "type". The Creature class should be the base class. The classes Demon, Elf, and Human should be derived from Creature. The classes Cyberdemon and Balrog should be derived from Demon. You will need to rewrite the getSpecies() and getDamage() functions so they are appropriate for each class.
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