Test: Recursion - 2 - Software Development MCQ

Which of the following is true about recursion?

What happens if a recursive function does not have a base case?

What is the output of the following code?

#include <iostream>

void printNumbers(int n) {
    if (n <= 0)
        return;

    std::cout << n << " ";
    printNumbers(n - 1);
}

int main() {
    printNumbers(5);
    return 0;
}

What is the output of the following code?
#include <iostream>

int sum(int n) {
    if (n == 0)
        return 0;
    
    return n + sum(n - 1);
}

int main() {
    std::cout << sum(4);
    return 0;
}

What is the output of the following code?
#include <iostream>

int factorial(int n) {
    if (n == 0 || n == 1)
        return 1;
    
    return n * factorial(n - 1);
}

int main() {
    std::cout << factorial(5);
    return 0;
}

What is the output of the following code?
#include <iostream>

void printPattern(int n) {
    if (n <= 0)
        return;
    
    std::cout << n << " ";
    printPattern(n - 2);
    std::cout << n << " ";
}

int main() {
    printPattern(5);
    return 0;
}

What is the output of the following code?
#include <iostream>

int fibonacci(int n) {
    if (n <= 1)
        return n;
    
    return fibonacci(n - 1) + fibonacci(n - 2);
}

int main() {
    std::cout << fibonacci(6);
    return 0;
}

What does the following code do?
#include <iostream>

int countDigits(int n) {
    if (n < 10)
        return 1;
    
    return 1 + countDigits(n / 10);
}

int main() {
    std::cout << countDigits(12345);
    return 0;
}

What does the following code do?
#include <iostream>

int power(int base, int exponent) {
    if (exponent == 0)
        return 1;
    
    return base * power(base, exponent - 1);
}

int main() {
    std::cout << power(2, 3);
    return 0;
}

What does the following code do?
#include <iostream>

int gcd(int a, int b) {
    if (b == 0)
        return a;
    
    return gcd(b, a % b);
}

int main() {
    std::cout << gcd(18, 24);
    return 0;
}

What does the following code do?
#include <iostream>

bool isPalindrome(const std::string& str, int start, int end) {
    if (start >= end)
        return true;
    
    return (str[start] == str[end]) && isPalindrome(str, start + 1, end - 1);
}

int main() {
    std::cout << isPalindrome("racecar", 0, 6);
    return 0;
}

What does the following code do?
#include <iostream>

void printBinary(int n) {
    if (n == 0)
        return;
    
    printBinary(n / 2);
    std::cout << n % 2;
}

int main() {
    printBinary(10);
    return 0;
}