C Program for Fibonacci Numbers With and Without Recursion

The numbers in the Fibonacci sequence follow the following pattern: every number after the first two is the sum of the two preceding ones. First few numbers in the Fibonacci series are as follows: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89. The first two numbers in the Fibonacci sequence are either 1 and 1, or 0 and 1, depending on the chosen starting point of the sequence.

In this blog, I am posting codes in C to generate the Fibonacci numbers with recursion and without recursion. The codes do not have all possible checks e.g. if n <0. These are just templates and can be modified to satisfy all cases.

C Program without recursion

#include<stdio.h>

int fibo(int a[], int k){
        return a[k-2]+a[k-1];
}

int main(){
        /* this program will print fibonacci series */
        int tot;
        printf("How many numbers you want in fibonacci series:");
        scanf("%d",&tot);
        int results[tot]; //to store values of fibonacci series
        results[0]=0;
        results[1]=1;
        for(int i=2;i<tot;i++)
                results[i]=fibo(results,i);
        printf ("First %d elements of fibonacci series are:", tot);
        for (int j=0;j<tot;j++)
                printf("%d ",results[j]);
        printf("\n");
        return 0;
}

$ ./tfunc.out
How many numbers you want in Fibonacci series:20
First 20 elements of Fibonacci series are:0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181

C Program with recursion

#include<stdio.h>

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

}

int main(){
        /* this program will print fibonacci series */
        int n;
        printf("How many numbers you want in fibonacci series:");
        scanf("%d",&n);
        printf("First %d elements in fibonacci series are:",n);
        for (int i=0;i<n;i++)
                printf("%d ",fibo(i));

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

$ ./recur.out
How many numbers you want in Fibonacci series:20
First 20 elements in Fibonacci series are:0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181