C++ Program to Find Fibonacci Numbers using Iteration

The term Fibonacci numbers is used in mathematics, which calculates the sum of two preceding numbers that starts from 0 and 1 and continues till based on the given number say num.

Mathemathematically, it is represented by:

Fn = Fn-1 + Fn-2

Let us take an example to understand the above formula based on fibonacci numbers.

F0 = 0 
F1 = 1 
F2 = F1 + F0 = 1 + 0 = 1 
F3 = F2 + F1 = 1 + 1 = 2 
F4 = F3 + F2 = 2 + 1 = 3 
and so on...

In this article, we will learn how to use iteration in fibonacci number in C++.

Example to Use Iteration in Fibonacci Numbers

In this example, we start with two initial variables say x (0) and y(1), and calculate the next term by the sum of two preceeding numbers. Then iterate the series for the fibonacci number through i on num and initialize the sum formula to z to get the expected outcome.

#include <iostream>
using namespace std;
void fib(int num) {
   int x = 0, y = 1;
   int z = 0;
   
   // iterate the series based on num
   for (int i = 0; i < num; i++) {
      cout << x << " ";
      z = x + y;
      x = y;
      y = z;
   }
}
int main() {
   int num = 8;
   
   // display the fibonacci series
   cout << "\nThe fibonacci series : " ;
   fib(num);
   return 0;
}

Output

The above program produces the following result:

The fibonacci series : 0 1 1 2 3 5 8 13