stack(simple)

#include <iostream>
#include <cstdlib>
using namespace std;

int top, i;
char key, temp;
char stack[10];

void push() {
    system("clear");
    if (top < 9)
    {
        cout << "masukkan sebuah karakter : ";
        cin >> temp;
        top++;
        stack[top] = temp;
        cout << "Data sudah masuk\n\n";
    }
    else {
        cout << "stack sudah penuh\n\n";
    }
}

void pop() {
    system("clear");
    if (top >= 0)
    {
        top--;
        cout << "Data sudah terhapus\n\n";
    }
    else {
        cout << "stack sudah kosong\n\n";
    }
}

void print() {
    system("clear");
    if (top >= 0)
    {
        cout << "Isi stack : \n\n";
        for (i = top; i >= 0; i--)
        {
            cout << " " << stack[i] << "\n";
        }
        cout << "\n\n";
    }
    else {
        cout << "stack masih kosong\n\n";
    }
}

int main() {
    system("clear");
    do {
        do {
                cout << "Program Stack\n\n"
                     << "1. Push\n"
                     << "2. Pop\n"
                     << "3. Print\n"
                     << "4. Exit\n\n"
                     << "Masukkan pilihan [1/2/3/4] : ";
                cin >> key;
            }
        while ((key != '1') && (key != '2') && (key != '3') && (key != '4'));

        if (key == '1')
        {
            push();
        }
        else if (key == '2')
        {
            pop();
        }
        else if (key == '3')
        {
            print();
        }
        else if (key == '4')
        {
            return 0;
        }
    }
    while (key = '4');

    return 0;
}