Example: Fibonacci Series - Iterative Function in C

// Fibonacci Series - Iterative Function
#include <stdio.h>

// Function to print the Fibonacci series up to 'n' terms iteratively
void printFibonacciIterative(int n) {
    // Step 1: Initialize the first two Fibonacci numbers
    int first = 0;
    int second = 1;
    int next;

    printf("Fibonacci Series (Iterative) up to %d terms: ", n);

    // Step 2: Handle edge cases for n=0 or n=1
    if (n <= 0) {
        printf("No terms to display.\n");
        return;
    } else if (n == 1) {
        printf("%d\n", first);
        return;
    }

    // Step 3: Print the first two terms
    printf("%d, %d", first, second);

    // Step 4: Loop from the 3rd term up to n terms
    for (int i = 3; i <= n; i++) {
        next = first + second;
        printf(", %d", next);
        first = second; // Move 'second' to 'first'
        second = next;  // Move 'next' to 'second'
    }
    printf("\n");
}

int main() {
    int numTerms;

    // Step 1: Prompt user for the number of terms
    printf("Enter the number of terms for Fibonacci Series: ");
    scanf("%d", &numTerms);

    // Step 2: Call the function to print the series
    printFibonacciIterative(numTerms);

    return 0;
}