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Changing class stats in another function?

Elarionus (32)
So I'm working on code to allow for multiple pets to be played with...I've gotten almost to where I need to be, but I still have two more problems. I need a random event to happen to a random pet and affect their statistics, and I need to have the "exit" option actually exit the program. I'm stuck on both of these, and I was hoping to get advice.

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  /*

03/20/2018
Section 02
Assignment 07
*/

#include<iostream>
#include<string>
#include<stdlib.h>
#include<time.h>
using namespace std;

// declaration of the pet class
class pet {
private:
	int hunger;           // private data member
	string species;       // private data member
	int happy;            // private data member
	int sleepy;           // private data member
public:
	pet();                // constructor
	void play();          // public member function
	void feed();          // public member function
	void nap();           // public member function
	void print();         // public member function
	void randomevent();
	int check_health();   // public member function
	string name;
};

pet petArray[4];
int petchoice;
int choice;
int health_check;

int main()
{
	petArray[0].name = "Shadow";
	petArray[1].name = "Freddie";
	petArray[2].name = "Moon Moon";
	petArray[3].name = "Sadie";

	do {
		cout << "\nWhich pet would you like to play with?\n";
		cout << "\n0 - Shadow\n1 - Freddie\n2 - Moon Moon\n3 - Sadie\n4 - Exit\n\n";
		cin >> petchoice;
		cout << endl;
		petArray[petchoice].print();
		cout << endl;
		cout << "What would you like to do with your pet?\n";
		cout << "Play (1) \nFeed (2) \nNap (3)\n";
		cin >> choice;
		switch (choice)
		{
		case 1:
			petArray[petchoice].play();
			break;
		case 2:
			petArray[petchoice].feed();
			break;
		case 3:
			petArray[petchoice].nap();
			break;
		}
		petArray[petchoice].print();
		health_check = petArray[0].check_health();
		petArray[0].randomevent();
	} while (choice != 0 && (!petArray[0].check_health() || !petArray[1].check_health() || !petArray[2].check_health() || !petArray[3].check_health()));
	cin.ignore();
	cout << "Press enter to exit." << endl;
	cin.ignore();
	return 0;
}

/* Constructor, creates a new pet with starting values. */
pet::pet() {

	hunger = 50;
	happy = 50;
	sleepy = 50;
}
/* Member function play(), allows playing with a pet. */
void pet::play() {
	int choice = 0;
	cout << "What should we play?\n";
	cout << "Fetch (1) \nRoll over (2) \n";
	cin >> choice;
	switch (choice) {
	case(1):
		cout << "\nGo get the ball! Fetch!\n";
		happy += 10;
		hunger += 5;
		break;
	case(2):
		cout << "\nCome on, roll over!\n";
		happy += 5;
		hunger += 1;
		break;
	default:
		cout << "Not a valid choice." << endl;
	}
}

/* Member function feed(), allows the user to feed a pet. */
void pet::feed()
{
	int choice = 0;
	cout << "What do you want to feed your pet?\n";
	cout << "1 - Health Food\n2 - Treat\n";
	cin >> choice;
	switch (choice)
	{
	case(1):
		cout << "I feel great!\n";
		happy -= 1;
		hunger -= 10;
		break;
	case(2):
		cout << "\nMMM, Yummy!\n";
		happy += 5;
		hunger -= 3;
		break;
	default:
		cout << "Invalid choice." << endl;
	}
}

/* Member function nap(), allows the user to have their pet take a nap. */
void pet::nap()
{
	cout << "Your pet is taking a nap! So relaxing!\n";
	hunger += 10;
	sleepy -= 20;
	happy += 5;
}

/* Member function print(), prints information about a pet. */
void pet::print() {
	cout << "\nYour pet " << name << " is \n";
	cout << "Happy: " << happy << endl;
	cout << "Hungry: " << hunger << endl;
	cout << "Sleepy: " << sleepy << endl;
}

/* Member function check_health(), checks the health of a pet. */
int pet::check_health() {
	if (hunger >= 100) {
		cout << "\nYour pet has starved.\n";
		return 1;
	}
	if (happy <= 0) {
		cout << "\nYour pet has died of a broken heart.\n";
		return 1;
	}
	if (sleepy >= 100) {
		cout << "\nYour pet has perished of exhaustion.\n";
		return 1;
	}
	return 0;
}

void pet::randomevent()
{
	int petRandom = rand() % 4;
	int choice = rand() % 4;
	switch (choice)
	{
	case 0:
		cout << "\n" << petArray[petRandom].name << " was sprayed by a skunk!\n";
		happy -= 20;
		break;
	case 1:
		cout << "\n" << petArray[petRandom].name << " is happy to be with you!\n";
		happy += 10;
		break;
	case 2:
		cout << "\n" << petArray[petRandom].name << " ate some human food and threw up!\n";
		happy += 5;
		hunger += 30;
		break;
	case 3:
		cout << "\n" << petArray[petRandom].name << " was barking all night!\n";
		sleepy += 20;
		break;
	}
}
Enoizat (1343)
but I still have two more problems

Optimist! :-)

I’ve added comments to your code, but first:
- I think you’d better keep your classes declarations and definitions closer to each other.
You use the randomevent() member as if it were a separate function, asking it to choose which class instance apply the changes to. It seems you missed the point of being a member function.

- I’m afraid you abused global variables: you could move all of them inside main().

- Meaningless comments worsen the code. What does “private data member” clarify?

- Magic numbers are insidious. What about substituting a const expression for them?
Es. constexpr int PETS_NUMBER = 4;

- Before using rand() you usually want to seed srand():
http://en.cppreference.com/w/cpp/numeric/random/srand
srand() is to be initialised only once.

Your code + some comments (starting with “-->”):
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/*
   03/20/2018
   Section 02
   Assignment 07
*/

#include<iostream>
#include<string>
#include<stdlib.h> // --> C header. Use the C++ corresponding
#include<time.h> // --> C header. Use the C++ corresponding

using namespace std; // --> C'mon! Just type std:: a few times and avoid this.

// declaration of the pet class
class pet {
private:
    int hunger;           // private data member
    string species;       // private data member
    int happy;            // private data member
    int sleepy;           // private data member
public:
    pet();                // constructor
    void play();          // public member function
    void feed();          // public member function
    void nap();           // public member function
    void print();         // public member function
    void randomevent();
    int check_health();   // public member function
    string name;
};

// --> Pointless global variables: move them inside main()
pet petArray[4];    // --> magic numbers often introduce hard to find bugs
int petchoice;
int choice;
int health_check;

int main()
{
    petArray[0].name = "Shadow";
    petArray[1].name = "Freddie";
    petArray[2].name = "Moon Moon";
    petArray[3].name = "Sadie";

    do {
        cout << "\nWhich pet would you like to play with?\n";
        cout << "\n0 - Shadow\n1 - Freddie\n2 - Moon Moon\n3 - Sadie\n4 - Exit\n\n";
        // --> What if I answer -1 or 5?
        cin >> petchoice;
        cout << endl;
        // --> QUESTION: I need to have the "exit" option actually exit the program
        // --> Hints: what does it happen if you return from main()?
        // -->        what does it happen if you break inside a loop?
        petArray[petchoice].print();
        cout << endl;
        cout << "What would you like to do with your pet?\n";
        cout << "Play (1) \nFeed (2) \nNap (3)\n";
        // --> What if I answer 0 or 4?
        cin >> choice;
        switch (choice) {
        case 1:
            petArray[petchoice].play();
            break;
        case 2:
            petArray[petchoice].feed();
            break;
        case 3:
            petArray[petchoice].nap();
            break;
        } // --> missing a default option.
        petArray[petchoice].print();
        // --> Are you really interested only in petArray[0] health at every iteration?
        health_check = petArray[0].check_health();
        // --> QUESTION: I need a random event to happen to a random pet
        // --> You need to choose your pet randomly here.
        // --> Suggestion: you need another function which returns a random number.
        // -->             That function doesn't need to be a member function.
        petArray[0].randomevent();
    } // --> 1) The exit option is stored in "petchoice", not in "choice"
      // --> 2) Use a loop to check all "health"(s) and break if needed
      while (   choice != 0
             && (   !petArray[0].check_health()
                 || !petArray[1].check_health()
                 || !petArray[2].check_health()
                 || !petArray[3].check_health() ) );
    cin.ignore();
    cout << "Press enter to exit." << endl;
    cin.ignore();
    return 0;
}

/* Constructor, creates a new pet with starting values. */
pet::pet() {

    hunger = 50;
    happy = 50;
    sleepy = 50;
}
/* Member function play(), allows playing with a pet. */
void pet::play() {
    int choice = 0;     // --> You are hiding a global variable here.
                        // --> Another good reason to avoid global variables.
    cout << "What should we play?\n";
    cout << "Fetch (1) \nRoll over (2) \n";
    cin >> choice;
    switch (choice) {
    case(1):
        cout << "\nGo get the ball! Fetch!\n";
        happy += 10;
        hunger += 5;
        break;
    case(2):
        cout << "\nCome on, roll over!\n";
        happy += 5;
        hunger += 1;
        break;
    default:
        cout << "Not a valid choice." << endl;
    }
}

/* Member function feed(), allows the user to feed a pet. */
void pet::feed()
{
    int choice = 0;
    cout << "What do you want to feed your pet?\n";
    cout << "1 - Health Food\n2 - Treat\n";
    cin >> choice;
    switch (choice) {
    case(1):    // --> parenthesis aren't a problem, but they are not required.
        cout << "I feel great!\n";
        happy -= 1;
        hunger -= 10;
        break;
    case(2):
        cout << "\nMMM, Yummy!\n";
        happy += 5;
        hunger -= 3;
        break;
    default:
        cout << "Invalid choice." << endl;
    }
}

/* Member function nap(), allows the user to have their pet take a nap. */
void pet::nap()
{
    cout << "Your pet is taking a nap! So relaxing!\n";
    hunger += 10;
    sleepy -= 20;
    happy += 5;
}

/* Member function print(), prints information about a pet. */
void pet::print() {
    cout << "\nYour pet " << name << " is \n";
    cout << "Happy: " << happy << endl;
    cout << "Hungry: " << hunger << endl;
    cout << "Sleepy: " << sleepy << endl;
}

/* Member function check_health(), checks the health of a pet. */
int pet::check_health() {
    if (hunger >= 100) {
        cout << "\nYour pet has starved.\n";
        return 1;
    }
    if (happy <= 0) {
        cout << "\nYour pet has died of a broken heart.\n";
        return 1;
    }
    if (sleepy >= 100) {
        cout << "\nYour pet has perished of exhaustion.\n";
        return 1;
    }
    return 0;
}

// --> This is a member function: it should not decide which class instance modify!!
void pet::randomevent()
{
    int petRandom = rand() % 4;
    int choice = rand() % 4;
    switch (choice) {
    case 0:
        cout << "\n" << petArray[petRandom].name << " was sprayed by a skunk!\n";
        happy -= 20;
        break;
    case 1:
        cout << "\n" << petArray[petRandom].name << " is happy to be with you!\n";
        happy += 10;
        break;
    case 2:
        cout << "\n" << petArray[petRandom].name << " ate some human food and threw up!\n";
        happy += 5;
        hunger += 30;
        break;
    case 3:
        cout << "\n" << petArray[petRandom].name << " was barking all night!\n";
        sleepy += 20;
        break;
    }
}

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