Loop Interview

#include <iostream>
#include <vector>

using namespace std;

// recursively display and remove the first integers of a vector
void recursive(vector<int> &arr) {
        //note: the pointer *arr.begin() == arr[0]
        //base case with a vector of 1 int
        if (arr.size() == 1) {
                cout << *arr.begin() << endl;
                //vector of 2 or more int
        } else {
                cout << *arr.begin() << endl;
                //remove first element and recurse
                arr.erase(arr.begin());
                recursive(arr);
        }
}

int main() {
        //While guessing game
        srand(time(nullptr));
        const int randomNumber = rand() % 10 + 1;
        int guess = 0;
        int guesses = 0;
        cout << "Guess a number between 1 and 10: " << endl;
        while (guess != randomNumber && guesses < 4) {
                cout << "You have " << 4 - guesses << " guesses left!" << endl;
                cin >> guess;
                guesses++;
                if (guess < randomNumber) {
                        cout << "Too low!" << endl;
                } else if (guess > randomNumber) {
                        cout << "Too high!" << endl;
                } else {
                        cout << "Congratulations! You guessed the number." << endl;
                }
        }

        //wait for input
        system("pause");

        //Do-While-Free-Trial
        char card = '-';
        do {
                if (card == '-') {
                        cout << "Thank you for activating your free Netflix trial." << endl;
                }
                cout << "One month of Netflix service used." << endl;
                cout << "Want to pay for another month? y or n" << endl;
                cin >> card;
        } while (card == 'y');
        cout << "No more Netflix for you!" << endl << endl;

        //windows-specific pause
        system("pause");
        cout << "Here's a demonstration of the same counting loop using 7 different loop styles:" << endl;
        system("pause");

        cout << "While loop with manual iteration" << endl;
        //WHILE loop
        int i = 0;
        while (i < 5) {
                cout << i << endl;
                i++;
        }

        system("pause");

        //DO-WHILE loop
        cout << endl << "Using Do-While Loop and manual iteration" << endl;
        int j = 0;
        do {
                cout << j << endl;
                j++;
        } while (j < 5);

        system("pause");

        //FOR loop
        cout << endl << "Using For Loop" << endl;
        for (int k = 0; k < 5; k++) {
                cout << k << endl;
        }

        //for use in recursion and for-each loop
        vector<int> numbers = {0, 1, 2, 3, 4};

        system("pause");

        //FOREACH loop
        cout << endl << "Using For-Each Loop and a vector" << endl;
        //int numbers[] = {0, 1, 2, 3, 4};
        for (const int number: numbers) {
                cout << number << endl;
        }

        system("pause");

        //RECURSIVE function call
        cout << endl << "Using Recursion through a vector" << endl;
        recursive(numbers);

        system("pause");

        //GOTO loop in Do-While style
        cout << endl << "Using post-test Goto Loop with manual iteration" << endl;
        int l = 0;
doloop:
        cout << l << endl;
        l++;
        if (l < 5) {
                goto doloop;
        }

        system("pause");

        //GOTO loop in While style
        cout << endl << "Using post-test Goto Loop with manual iteration" << endl;
        int m = 0;
whileloop:
        if (m < 5) {
                cout << m << endl;
                m++;
                goto whileloop;
        }

        system("pause");

}