C Program to generate Fibonacci sequence

What is the Fibonacci sequence?

In the Fibonacci series, each number is the sum of the two previous numbers. The first two numbers in the Fibonacci series are 0 and 1.

The sequence Fn of Fibonacci numbers is defined by the recurrence relation:

Fn = Fn-1 + Fn-2  ( where, n > 1)

with seed values

F0 = 0 and F1 = 1.

 

The beginning of the sequence is thus:

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ……..

 

Algorithm to generate Fibonacci sequence using C program:

1. Get the Fibonacci series limit from the user, say n.
2. Assign “preValue1” = 0, “preValue2” = 1.
3. Assign the addition of”preValue1 and preValue2” to “next”.
   next = preValue1 + preValue2
4. Swap “preValue2” to “preValue1” and “next ” to “preValue2”.
5. Repeat steps 3 and 4 till n.

 

See the C program to generate the Fibonacci sequence based on the number of terms entered by the user.

#include <stdio.h>
int main()
{
    int num, i = 0, next, preValue1 = 0, preValue2 = 1;

    printf("Enter no. of terms: ");
    scanf("%d",&num);

    if(num < 0)
    {
        printf("Enter valid number\n");
    }
    else
    {
        while(i < num)
        {
            if(i <= 1)
            {
                next = i;
            }
            else
            {
                next = preValue1 + preValue2;
                preValue1 = preValue2;
                preValue2 = next;
            }
            printf("%d \t", next);
            i++;
        }
    }


    return 0;
}

Output:

Enter no. of terms: 5
0 1 1 2 3