Lecture 1, 2 and 3: Recursion Level 1 (till Fibonacci number) #

What is the output of the following program?

#include <iostream>
using namespace std;

int func(int num)
{
    return func(num- 1);
}

int main()
{
    int num = 5;
    int ans = func(num - 1);
    cout << ans;
}

Options

a. Compilation Error
b. Runtime Error
c. 5
d. None of these

b. Runtime Error
No anchor condition, so recursion calls will never end. Hence Runtime error.

What is the output of the following program?

#include <iostream>
using namespace std;

void print(int n)
{
    if(n < 0)
    {
        return;
    }
    cout << n << " ";
    print(n - 2);
}

int main()
{
    int num = 5;
    print(num);
}

Options

a. Runtime error
b. 5 4 3 2 1
c. 5 3 1
d. None of these

c. 5 3 1
Simple recursion.

What is the output of the following program?

#include <iostream>
using namespace std;

void print(int n)
{
    if(n < 0)
    {
        return;
    }
    if(n == 0)
    {
        cout << n << “ “;
        return;
    }
    print(n --);
    cout << n << “ “;
}

int main()
{
    int num = 3;
    print(num);
}

Options

a. Runtime error
b. 3 2 1
c. 3 3 3
d. 0 1 2 3

a. Runtime Error
As we are passing n--(post -), so n is passed everytime in the recursion call. And as n is not decreasing, it is an infinite recursion.