Fibonacci series through recursion (C++ Tutorial)

Fibonacci series through recursion

fibonacciRecursive() calculates the fibonacci number of the given number recursively.

For example,

If the number is 0 then it will return  0,

If the number is 1 then it will return  1,

If the number is 2 then it will return  1,

If the number is 3 then it will return  2,

If the number is 4 then it will return  3,

If the number is 5 then it will return  5,

If the number is 6 then it will return  8,

If the number is 7 then it will return 13,

If the number is 8 then it will return 21,

If the number is 9 then it will return 34.

Code of fibonacciRecursive()

unsigned long fibonacciRecursive( unsigned long number )

{

if ( number == 0 || number ==1 )

            return number;

      else

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

}

Summary of fibonacciRecursive()

fibonacciRecursive() is a recursive function with 2 parts;

first part is the base case – if the number is equal to 0 or 1, then this function will return 1.

fibonacciRecursive( 0 ) = 1

fibonacciRecursive( 1 ) = 1

Second part consists of recursive calls as mentioned below:

fibonacciRecursive( number - 1 ) + fibonacciRecursive( number - 2 )

Example (C++)

#include "stdafx.h"

#include "iostream"

#include "iomanip"

#include "conio.h"

using namespace std;

unsigned long fibonacciRecursive( unsigned long number )

{

if ( number == 0 || number ==1 )

            return number;

      else

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

}

int main()

{

      for( unsigned long i = 0; i < 10; i++ )

            cout << fibonacciRecursive( i ) << setw(4) ;

      cout << endl;

      _getche();

      return 0;

}

Output

0   1   1   2   3   5   8  13  21  34