  Fibonacci Series

Fibonacci Series in C: In case of fibonacci series, next number is the sum of previous two numbers for example 0, 1, 1, 2, 3, 5, 8, 13, 21 etc. The first two numbers of fibonacci series are 0 and 1.

There are two ways to write the fibonacci series program:

• Fibonacci Series without recursion
• Fibonacci Series using recursion

Fibonacci Series in C without recursion

Let’s see the fibonacci series program in c without recursion.

1. #include<stdio.h>
2. #include<conio.h>
3. void main()
4. {
5.  int n1=0,n2=1,n3,i,number;
6.  clrscr();
7.  printf(“Enter the number of elements:”);
8.  scanf(“%d”,&number);
9.  printf(“\n%d %d”,n1,n2);//printing 0 and 1
10.  for(i=2;i<number;++i)//loop starts from 2 because 0 and 1 are already printed
11.  {
12.   n3=n1+n2;
13.   printf(” %d”,n3);
14.   n1=n2;
15.   n2=n3;
16.  }
17. getch();
18. }

Output:

Enter the number of elements:15
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377

Fibonacci Series using recursion in C

Let’s see the fibonacci series program in c using recursion.

1. #include<stdio.h>
2. #include<conio.h>
3. void printFibonacci(int n){
4.     static int n1=0,n2=1,n3;
5.     if(n>0){
6.          n3 = n1 + n2;
7.          n1 = n2;
8.          n2 = n3;
9.          printf(“%d “,n3);
10.          printFibonacci(n-1);
11.     }
12. }
13. void main(){
14.     int n;
15.     clrscr();
16.     printf(“Enter the number of elements: “);
17.     scanf(“%d”,&n);
18.     printf(“Fibonacci Series: “);
19.     printf(“%d %d “,0,1);
20.     printFibonacci(n-2);//n-2 because 2 numbers are already printed
21.     getch();
22. }

Output:

Enter the number of elements:15
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377