Write a Program in C++ That Do Recursive Function Fibonacci

// Recursive function fibonacci.

#include <iostream>

using namespace std;

unsigned long fibonacci( unsigned long ); // function prototype

int main()

{

   // calculate the fibonacci values of 0 through 10

   for ( unsigned int counter = 0; counter <= 10; ++counter )

      cout << "fibonacci( " << counter << " ) = "

         << fibonacci( counter ) << endl;

   // display higher fibonacci values

   cout << "\nfibonacci( 20 ) = " << fibonacci( 20 ) << endl;

   cout << "fibonacci( 30 ) = " << fibonacci( 30 ) << endl;

   cout << "fibonacci( 35 ) = " << fibonacci( 35 ) << endl;

} // end main

// recursive function fibonacci

unsigned long fibonacci( unsigned long number )

{

   if ( ( 0 == number ) || ( 1 == number ) ) // base cases

      return number;

   else // recursion step

      return fibonacci( number - 1 ) + fibonacci( number - 2 );

} // end function fibonacci