Example: Fibonacci Series using Recursion in C

// Fibonacci Series using Recursion
#include <stdio.h>

// Function to calculate the nth Fibonacci number recursively
int fibonacci(int n) {
    // Step 1: Define the base cases
    // The first two Fibonacci numbers are 0 and 1
    if (n <= 1) {
        return n; // fib(0) = 0, fib(1) = 1
    } 
    // Step 2: Define the recursive step
    // For n > 1, fib(n) is the sum of the two preceding numbers
    else {
        return fibonacci(n - 1) + fibonacci(n - 2);
    }
}

int main() {
    // Step 1: Declare the number of terms to print
    int terms = 10; 
    int i; // Loop counter

    // Step 2: Print a header for the output
    printf("Fibonacci Series up to %d terms:\n", terms);

    // Step 3: Loop through each term from 0 to terms-1
    // and call the fibonacci function to get its value
    for (i = 0; i < terms; i++) {
        printf("%d ", fibonacci(i));
    }
    printf("\n"); // Print a newline character at the end

    return 0; // Indicate successful execution
}