20.C Program to Display Fibonacci Sequence

C Program to Display Fibonacci Sequence

Example on how to display the Fibonacci sequence of first n numbers (entered by the user) using loop. Also in different example, you learn to generate the Fibonacci sequence up to a certain number.

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

• C Programming Operators
• C programming while and do...while Loop
• C Programming for Loop
• C Programming break and continue Statement

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

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

Visit this page to learn about Fibonacci sequence.

Example #1: Fibonacci Series up to n number of terms

#include <stdio.h>
int main()
{
    int i, n, t1 = 0, t2 = 1, nextTerm = 0;

    printf("Enter the number of terms: ");
    scanf("%d", &n);

    printf("Fibonacci Series: ");

    for (i = 1; i <= n; ++i)
    {
        // Prints the first two terms.
        if(i == 1)
        {
            printf("%d, ", t1);
            continue;
        }
        if(i == 2)
        {
            printf("%d, ", t2);
            continue;
        }
        nextTerm = t1 + t2;
        t1 = t2;
        t2 = nextTerm;
        printf("%d, ", nextTerm);
    }
    return 0;
}

Output

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

Example #2: Program to Generate 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, 

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