C program to generate Fibonacci series using recursion

In this article we will learn to implement a C program to generate Fibonacci series using recursion. A C program is provided below to generate a Fibonacci series using both recursive and non-recursive functions.

Program is as follows:

/*
 * C program to generate fibonacci sequence using recursive and non-recursive functions
 * Author: P.S.SuryaTeja
*/
#include <stdio.h>
#include <conio.h>
#include <math.h>
#include <stdlib.h>

void fib(int n)
{
	int a = 0, b = 1, c, count = 3;	
	if(n == 1)
		printf("0");
	else if(n == 2)
		printf("0 1");
	else
	{
		printf("0 1 ");
		while(count <= n)
		{
			c = a + b;
			printf("%d ", c);
			a = b;
			b = c;
			count++;
		}
	}
}

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

int main(int argc, char **argv)
{
	int n, count = 3;
	printf("Enter a number: ");
	scanf("%d", &n);
	printf("\nNon-recursive fibonacci sequence upto %d terms: \n", n);
	fib(n);
	printf("\nRecursive fibonacci sequence upto %d terms: \n", n);
	if(n == 1)
		printf("0");
	else if(n == 2)
		printf("0 1");
	else
	{
		printf("0 1 ");
		while(count <= n)
		{
			printf("%d ", rfib(count));
			count++;
		}
	}
    getch();
    return 0;
}

Input and output for the above program is as follows:

Enter a number: 10

Non-recursive fibonacci sequence upto 10 terms:
0 1 1 2 3 5 8 13 21 34
Recursive fibonacci sequence upto 10 terms:
0 1 1 2 3 5 8 13 21 34

Suryateja Pericherla

Suryateja Pericherla, at present is a Research Scholar (full-time Ph.D.) in the Dept. of Computer Science & Systems Engineering at Andhra University, Visakhapatnam. Previously worked as an Associate Professor in the Dept. of CSE at Vishnu Institute of Technology, India.

He has 11+ years of teaching experience and is an individual researcher whose research interests are Cloud Computing, Internet of Things, Computer Security, Network Security and Blockchain.

He is a member of professional societies like IEEE, ACM, CSI and ISCA. He published several research papers which are indexed by SCIE, WoS, Scopus, Springer and others.