C Program to display Fibonacci series

June 5, 2021

In this tutorial, we will learn two following ways to display Fibonacci series in C programming language:
1) Using For loop
2) Using recursion

Fibonacci Series in C using loop

A simple for loop to display the series. Program prompts user for the number of terms and displays the series having the same number of terms.

#include<stdio.h>
int main()
{
    int count, first_term = 0, second_term = 1, next_term, i;
 
    //Ask user to input number of terms 
    printf("Enter the number of terms:\n");
    scanf("%d",&count);
 
    printf("First %d terms of Fibonacci series:\n",count);
    for ( i = 0 ; i < count ; i++ )
    {
       if ( i <= 1 )
          next_term = i;
       else
       {
          next_term = first_term + second_term;
          first_term = second_term;
          second_term = next_term;
       }
       printf("%d\n",next_term);
    }
 
    return 0;
}

Output:

Enter the number of terms: 8
First 8 terms of Fibonacci series:
0
1
1
2
3
5
8
13

Program to display Fibonacci series using recursion

Here we are using a user defined function fibonacci_series() that calls itself recursively, in order to display series for the entered number of terms.

#include<stdio.h>
int fibonacci_series(int);
int main()
{
   int count, c = 0, i;
   printf("Enter number of terms:");
   scanf("%d",&count);
 
   printf("\nFibonacci series:\n");
   for ( i = 1 ; i <= count ; i++ )
   {
      printf("%d\n", fibonacci_series(c));
      c++; 
   }
 
   return 0;
}
int fibonacci_series(int num)
{
   if ( num == 0 )
     return 0;
   else if ( num == 1 )
     return 1;
   else
     return ( fibonacci_series(num-1) + fibonacci_series(num-2) );
}

Output:

Enter number of terms: 6
Fibonacci series:
0
1
1
2
3
5

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