solving fibonacci sequence recursively

solving fibonacci sequence recursively using C++ implementation
cpp code

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

//function declaration
double fibonacci(unsigned int n);

int main()
{
	int n;
	
	cout << "Enter a number: ";
	cin >> n;
	
	//An 'If' condition to prevent the user from entering -ve integers
	if (n<0)
		cout << "Please Enter a positive integer!" << endl;
	else
		cout << "The fibonacci number is " << fibonacci(n) << endl;
			
	cout << "The fibonacci sequence is as follows:" << endl;
	
	//Print Table Heading
	cout << setw(10) << "n" << setw(10) << " | " << setw(10) << "F(n)" << endl;
       	cout << "-----------------------------------------" << endl;
	
	//A Loop to print fibonacci numbers until 'n' in a tabular form
	for(int i=0;i<=n;i++)
		cout << setw(10) << i << setw(10) << " | " << setw(10) << fibonacci(i) << endl;

	return 0;
}

//function definition
double fibonacci(unsigned int n)
{
	//See what 'n' is
	switch(n)
	{
		//If n=0 F(n)=0
		case 0:
			return 0;
			break;
			
		//if n=1 F(n)=1
		case 1:
			return 1;
			break;
			
		//Otherwise solve recursively
		default:
			return fibonacci(n-1)+fibonacci(n-2);
			break;
	}
}