printing fibonacci series using recursion in c++ [closed]

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I just started learning c++ by myself. I am trying to practice recusion now. I want to print all n(input by user) fibonacci numbers using recursion, but it does not work. Could you help me? Thank you!!

#include <iostream>
using namespace std;
int fibonacci(int n)
{   
    if (n==1)
    {
        return 1;
        cout<<1<<" ";
    }   
    else if (n==2)
    {
        return 1;
        cout<<1<<" ";
    }
    else
    {
        return (fibonacci(n-1)+fibonacci(n-2));
        cout<<fibonacci(n-1)+fibonacci(n-2)<<" ";
    }
}
int main()
{
    int n;
    cin>>n;
    fibonacci(n);
    return 0;
}

Answer 1

If you look at Rosetta Code page for Fibonacci, you see that F(0) == 0 and F(1) == 1.

int fibonacci(int n)
{   

    if (n == 0)
    {
        return 0;
    }   
    else if (n == 1)
    {
        return 1;
    }
    else
    {
        return fibonacci(n-1) + fibonacci(n-2);
    }

    return fib;
}

In this case, you have a function that will calculate the fibonacci number at a specific position, right?

So now you need to calculate them and then print them:

int main()
{
    int n;
    cin >> n;

    if (n < 0)
    {
        return -1; // This means there was an error
    }

    for (int i = 1; i < n; ++i)
    {
        cout << fibonacci(i) << " ";
    }

    return 0;
}

Note that this is not the most efficient way to do it at all, but it kinda helps you understand how recursion works.

Answer 2

No need for cout in Fibonacci function, only cout by loop in int main()... also change IF condition in Fibonacci function to <=0 otherwise it will give you a segmentation fault (error)

#include <iostream>
using namespace std;
int fibonacci(int n)
{   
    if (n<=0)
    {
        return 0;
    //    cout<<1<<" ";
    }   
    else if (n==1)
    {
        return 1;
    //    cout<<1<<" ";
    }
    else
    {
        return (fibonacci(n-1)+fibonacci(n-2));
    //   cout<<fibonacci(n-1)+fibonacci(n-2)<<" ";
    }
}
int main()
{
    int n;
    cin>>n;
    for (int x = 0; x < n; x++)
    cout << fibonacci(x) << " ";
    cout << endl;

  return 0;
}

Answer 3

Even if you place cout before your return statement, your code will not give you the fibonacci series in the right order. Let's say you ask for fibonacci(7). It will print all the intermediate computations for fibonacci(6), and then it will print all 1's for fibonacci(5).