Fibonacci Series in C Programming Language

If you’ve ever had a programming interview, you’re aware that many C programming interviews include a question about writing a Fibonacci sequence program or Fibonacci series in c language. Many people are perplexed by this seemingly basic question.

In this article, we will put a light on how to implement the Fibonacci series program in C.

In C, the Fibonacci sequence is a number sequence in which the next term is the sum of the two previous terms. In the Fibonacci series, the first two terms are 0 and 1, followed by 1, the Fibonacci sequence is composed of the numbers 0,1,2,3,5,8,13,21….

Algorithm of Fibonacci series in c

Step 1; Enter the integer variables A, B, and C.

Step 2; make A=0 and B=0.

DISPLAY A and B in step 3

Step 4 C= A PLUS B

Pseudo code of Fibonacci series

Fibonacci number

Display 0 if the Fibonacci number is less than one

Display 1 if the Fibonacci number is equal to 1.

Display 1,1 if the Fibonacci number is equal to 2.

If the Fibonacci number is bigger than 2, it is said to be Fibonacci.



Pre- and post display

From zero to the -2nd Fibonacci number

Fib stands for; before and after;

Fibonacci series C program

Fibonacci series is a number sequence produced by adding the two preceding integers in the series. Zero and one are the first two terms, respectively. The following term is created by simply adding the two preceding terms together.

The Fibonacci series program can be written in two ways,

  • Without recursion
  • Fibonacci series in c using recursion

The Fibonacci sequence is made up of the numbers, 0, 1, 2, 3, 5, 8, 13, 21, and 34, and so on.

  • By adding the two numbers before it, the following number is found;
  • 2 are calculated by multiplying the two integers that come before it.
  • The number 3 is calculated by adding the two numbers that come before it.
  • [2 and 3] and so forth….

All variables are declared first in the programming above. First, we set the value for the first and second variables, which will be used to produce more terms. Then we define the term n, which will be used to keep track of the number of terms. To represent the sum of the two digits, we use the sum of the terms. The final term is I, which is utilized for loop iteration.

We accept the user’s term count and store it in the variable n. then we have a loop that runs from 0 to the number of terms the users have requested, which is n.

Also Read: Data Types in C Language

We have if statements inside the loop that checks whether the value is less than one. Depending on the number of terms. 0 or 1 is printed. When there is more than one, it is used to print the initial zero and one.

If the number of terms is larger than one, the otherwise part of the loop is run, which assigns the sum of the variable first and second to the variable sum. The sum variable is the next term.

The value of the second term is assigned to the first term in the next section, followed by the value of the sum to the second term. This is done because the previous two values is written for the next term. This is the total value if we assign 0 and 1 to the first and second, the value of the first will be 1 after this step, and the value of the second will likewise be 1 because the cumulative value is 1.

We print the sum value after entering the else part. This is repeated until the value of I equals n, at which point the loop breaks and the program terminates.

How do you calculate Fibonacci?

  • The number 0,1,2,3,5,8,13,21,34… is the Fibonacci series in order.
  • By adding the two numbers before it, the next number is discovered; 2 is computed by adding the two number before it. [1plus1]
  • [2plus3] is calculated by adding the two numbers before it.

Fibonacci series program in C without recursion

        [First-number=0] [Int second number=0

][Int third-number

Printf [; Fibonacci sequence numbers]

Fibonacci series in c using Recursion

Recursion is another approach to program the production of the Fibonacci series. The technique of repeating an item in a self-similar manner is known as recursion.

When a program permits you to call a function inside another function, this is referred to as a recursive call of the function.

The Fibonacci sequence is generated via recursion in this application. The function Fibonacci is called repeatedly until the output is obtained. We first check whether the integer n is zero or one in the function. If yes, the value of in is returned. If not, we call Fibonacci with the values n-1 and n-2 in a recursive manner.

Fibonacci series using recursion in C

Fibonacci [int number] void print if [number is smaller than 0] set first- number=0,

Second-number=1, and


Fibonacci series in C using a for loop

The startup phase is only performed once throughout the entire program. You can initialize and declare variables for the code at this phase. The situation will then be assessed. If the condition is true, the code inside the block for loop will be executed. If the condition is false, the code after the loop will be executed instead of the loop code.

The increment statement will be executed after the loop. The condition will be verified once more after that. If the condition is true, the loop will be executed, and the body of the loop, an increment statement, and the condition will be repeated. When the condition is false, the loop ends.

Fibonacci series using while loop

The while loop executed numerous items based on the condition in the while loop. If the condition is true, the code inside the while loop block will be performed. If the condition is false, it skips through the while loop and goes straight to the code after it.


That’s all about the Fibonacci series in C language. Hope this article will cover all of your questions.