Fibonacci Series in Python, C, C++, Java [Loop & Recursion]

Introduction

The Fibonacci series is one of the most popular programming problems in college exams like SRMU, BBD, Integral University, and in company coding rounds.

The Fibonacci sequence is:

0, 1, 1, 2, 3, 5, 8, 13, ...

• First two numbers are 0 and 1.
• Every next number is the sum of the previous two.

👉 Also check: Even Odd Program in Python, C, C++, Java and Factorial Program in Python.

Logic Behind Fibonacci Series

• Base Condition: F(0) = 0, F(1) = 1
• Recursive Formula: F(n) = F(n-1) + F(n-2)

There are 3 common ways to implement it:

1. Using Loop (Iteration)
2. Using Function
3. Using Recursion

---

Fibonacci in Python

1. Using Loop

# Fibonacci Series in Python using Loop

n = int(input("Enter the number of terms: "))
a, b = 0, 1

print("Fibonacci Series:", end=" ")
for _ in range(n):
    print(a, end=" ")
    a, b = b, a + b

Using Function

# Fibonacci Series in Python using Function

def fibonacci(n):
    a, b = 0, 1
    for _ in range(n):
        print(a, end=" ")
        a, b = b, a + b

n = int(input("Enter the number of terms: "))
fibonacci(n)

Using Recursion

# Fibonacci Series in Python using Recursion

def fib(n):
    if n <= 1:
        return n
    else:
        return fib(n-1) + fib(n-2)

n = int(input("Enter number of terms: "))

print("Fibonacci Series:", end=" ")
for i in range(n):
    print(fib(i), end=" ")

Fibonacci in C

1. Using Loop

#include <stdio.h>

int main() {
    int n, a = 0, b = 1, c;
    printf("Enter number of terms: ");
    scanf("%d", &n);

    printf("Fibonacci Series: ");
    for (int i = 0; i < n; i++) {
        printf("%d ", a);
        c = a + b;
        a = b;
        b = c;
    }
    return 0;
}

Using Function

#include <stdio.h>

void fibonacci(int n) {
    int a = 0, b = 1, c;
    for (int i = 0; i < n; i++) {
        printf("%d ", a);
        c = a + b;
        a = b;
        b = c;
    }
}

int main() {
    int n;
    printf("Enter number of terms: ");
    scanf("%d", &n);
    fibonacci(n);
    return 0;
}

Using Recursion

#include <stdio.h>

int fib(int n) {
    if (n <= 1)
        return n;
    return fib(n - 1) + fib(n - 2);
}

int main() {
    int n;
    printf("Enter number of terms: ");
    scanf("%d", &n);

    printf("Fibonacci Series: ");
    for (int i = 0; i < n; i++) {
        printf("%d ", fib(i));
    }
    return 0;
}

Fibonacci in C++

Using Loop

#include <iostream>
using namespace std;

int main() {
    int n, a = 0, b = 1, c;
    cout << "Enter number of terms: ";
    cin >> n;

    cout << "Fibonacci Series: ";
    for (int i = 0; i < n; i++) {
        cout << a << " ";
        c = a + b;
        a = b;
        b = c;
    }
    return 0;
}

Using Function

#include <iostream>
using namespace std;

void fibonacci(int n) {
    int a = 0, b = 1, c;
    for (int i = 0; i < n; i++) {
        cout << a << " ";
        c = a + b;
        a = b;
        b = c;
    }
}

int main() {
    int n;
    cout << "Enter number of terms: ";
    cin >> n;
    fibonacci(n);
    return 0;
}

Using Recursion

#include <iostream>
using namespace std;

int fib(int n) {
    if (n <= 1)
        return n;
    return fib(n - 1) + fib(n - 2);
}

int main() {
    int n;
    cout << "Enter number of terms: ";
    cin >> n;

    cout << "Fibonacci Series: ";
    for (int i = 0; i < n; i++) {
        cout << fib(i) << " ";
    }
    return 0;
}

Fibonacci in Java

1. Using Loop

import java.util.Scanner;

public class FibonacciLoop {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter number of terms: ");
        int n = sc.nextInt();
        int a = 0, b = 1, c;

        System.out.print("Fibonacci Series: ");
        for (int i = 0; i < n; i++) {
            System.out.print(a + " ");
            c = a + b;
            a = b;
            b = c;
        }

        sc.close();
    }
}

Using Function

import java.util.Scanner;

public class FibonacciFunction {
    static void fibonacci(int n) {
        int a = 0, b = 1, c;
        for (int i = 0; i < n; i++) {
            System.out.print(a + " ");
            c = a + b;
            a = b;
            b = c;
        }
    }

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter number of terms: ");
        int n = sc.nextInt();

        fibonacci(n);

        sc.close();
    }
}

Using Recursion

import java.util.Scanner;

public class FibonacciRecursion {
static int fib(int n) {
if (n <= 1)
return n;
return fib(n – 1) + fib(n – 2);
}

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    System.out.print("Enter number of terms: ");
    int n = sc.nextInt();

    System.out.print("Fibonacci Series: ");
    for (int i = 0; i < n; i++) {
        System.out.print(fib(i) + " ");
    }

    sc.close();
}
}

---

---

Why This Question is Important?

• College Exams → Universities like SRMU, BBD, Integral ask Fibonacci frequently in lab tests.
• Placements → Companies use it to test recursion & iteration knowledge.
• DSA Foundation → It builds the base for solving advanced recursion and DP problems.

👉 Next, try solving:

• Palindrome Program in Java
• Armstrong Number in C

For more references, check GeeksforGeeks Fibonacci Series.