C Program to Display Fibonacci Sequence

In this example, you will learn to display the Fibonacci sequence of first n numbers (entered by the user).
The Fibonacci Sequence

To understand this example, you should have the knowledge of the following C programming topics:

The Fibonacci sequence is a sequence where the next term is the sum of the previous two terms. The first two terms of the Fibonacci sequence are 0 followed by 1.

The Fibonacci sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21

Visit this page to learn about the Fibonacci sequence.


Fibonacci Series up to n terms

#include <stdio.h>
int main() {
    int i, n, t1 = 0, t2 = 1, nextTerm;
    printf("Enter the number of terms: ");
    scanf("%d", &n);
    printf("Fibonacci Series: ");

    for (i = 1; i <= n; ++i) {
        printf("%d, ", t1);
        nextTerm = t1 + t2;
        t1 = t2;
        t2 = nextTerm;
    }

    return 0;
}

Output

Enter the number of terms: 10
Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 

Fibonacci Sequence Up to a Certain Number

#include <stdio.h>
int main() {
    int t1 = 0, t2 = 1, nextTerm = 0, n;
    printf("Enter a positive number: ");
    scanf("%d", &n);

    // displays the first two terms which is always 0 and 1
    printf("Fibonacci Series: %d, %d, ", t1, t2);
    nextTerm = t1 + t2;

    while (nextTerm <= n) {
        printf("%d, ", nextTerm);
        t1 = t2;
        t2 = nextTerm;
        nextTerm = t1 + t2;
    }

    return 0;
}

Output

Enter a positive integer: 100
Fibonacci Series: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89,