C Exercises: Find the sum of the even-valued terms from the terms in the Fibonacci sequence

C Programming Practice: Exercise-18 with Solution

In mathematics, the Fibonacci numbers, commonly denoted F_n form a sequence, called the Fibonacci sequence, such that each number is the sum of the two preceding ones, starting from 0 and 1. That is, and for n > 1. By starting with 1 and 2, the first 10 terms will be: 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, . . .
Write a C programming to find the sum of the even-valued terms from the terms in the Fibonacci sequence whose values do not exceed one million.

C Code:

#include <stdio.h>
int main(void)
{
  unsigned int x1 = 1, x2 = 1, x3 = 2, num_sum = 0;
  while (x3 < 10) {
    x3 = x1 + x2;
    num_sum += x3 * !(x3%2);
    x1 = x2;
    x2 = x3;
  }
  printf("%u\n", num_sum);
  return 0;
}

Sample Output:

10

Flowchart:

C Programming Code Editor:

Contribute your code and comments through Disqus.

Previous: Write a C programming to find the sum of all the multiples of 3 or 7 below 100.
Next: Write a C programming to find the largest prime factor of the number 438927456?.