C Program to Print Fibonacci Series - Iterative Approach

Print Fibonacci Series Iteratively

#include <stdio.h>

int main() {
    int n;
    // First two terms of the sequence
    long long t1 = 0, t2 = 1, nextTerm;

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

    if (n <= 0) {
        printf("Please enter a positive integer.\n");
        return 0;
    }

    printf("Fibonacci Series: ");

    // Print the first term
    if (n >= 1) {
        printf("%lld ", t1);
    }

    // Print the second term
    if (n >= 2) {
        printf("%lld ", t2);
    }

    // Compute and print the rest of the terms
    for (int i = 3; i <= n; ++i) {
        nextTerm = t1 + t2;
        printf("%lld ", nextTerm);
        t1 = t2;       // Move t2 to t1
        t2 = nextTerm; // Update t2 to nextTerm
    }

    printf("\n");
    return 0;
}

Enter the number of terms: 7
Fibonacci Series: 0 1 1 2 3 5 8 
        

Practice: Fibonacci Series

The Fibonacci sequence starts with 0 and 1, and each subsequent term is the sum of the previous two. By keeping track of the current and previous terms, you can generate the series iteratively without needing recursion. Using a long long type allows the program to handle larger numbers.