C program to display Fibonacci series

In this example, you are going to learn in depth about C program to display Fibonacci series till the number entered by the user.

C program to display Fibonacci series

Fibonacci sequence is the series of integers where next number in series is formed by adding previous two numbers.

0   1   (0+1)1   (1+1)2   (1+2)3   (2+3)5

As shown above, the next number is found by adding up the two numbers before it. For example:

  • 2 is found by adding the two numbers before it (1+1)
  • 3 is found by adding the two numbers before it (1+2),
  • And the 5 is (2+3), and so on

Now, let’s implement this logic into C code to get Fibonacci series.

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C program to display Fibonacci series up to number entered by the user

//C program to implement fibonacci series

#include<stdio.h>

int main()
{
   int oldNum, newNum, fibNum, maxNum;

   //Enter maximum number till you want to generate fibonacci series
   printf("\nEnter number: ");
   scanf("%d", &maxNum);

   oldNum = 0;
   newNum = 1;
   fibNum = oldNum + newNum;

   printf("\nFibonacci Series: %d %d ", oldNum, newNum);

   //while is true till fibNum is less than maxNum and fibNum is calculated
   while(fibNum <= maxNum)
   {
      printf("%d ", fibNum);
      oldNum = newNum;
      newNum = fibNum;
      fibNum = oldNum + newNum;
   }

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

Output

C programming fibonacci series