# C++ - ProjectEuler.net, Problem 2

Public domain

``````/*
* projecteuler.net, Problem 2 :
*
* By considering the terms in the Fibonacci sequence whose values do not
* exceed four million, find the sum of the even-valued terms.
*
* Each new term in the Fibonacci sequence is generated by adding the
* previous two terms. By starting with 1 and 2, the first 10 terms will be:
*
* 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
*
* By considering the terms in the Fibonacci sequence whose values do not
* exceed four million, find the sum of the even-valued terms.
*
*/

#include <iostream>
#include <iomanip>

using namespace std;

main()
{
const int max = 4000000;
int sum = 0;

for (int i = 1, j = 1; i < max; i += j) {
// check for even number
if (i % 2 == 0) {

// print plus sign before every number
// except the first one
if (sum != 0)
cout << " + ";

cout << i;
sum += i;
}

// swapping two variables
i -= j += i -= j = -j;

}

cout << " = " << sum << endl;
}
``````

Output :

``````2 + 8 + 34 + 144 + 610 + 2584 + 10946 + 46368 + 196418 + 832040 + 3524578 = 4613732
``````