Project Euler Example 2 using PHP

Project euler

In project Euler example 2 the question is very simple:

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.

Now to find a Fibonacci sequence

function fabonnaciNumber()
{
    $a = 1;
    $b = 1;
    $sum = 0;
    $c = $a + $b;
    while($c < 4000000){
        if($c % 2 == 0){
            $sum += $c; // $sum = $sum + $c;
            $a = $b + $c;
            $b = $a + $c;
            $c = $a + $b;
        }
    }
    echo $sum;
}

echo fabonnaciNumber();

In this function, the variable $a is initialized with value 1 and $b is also initialized with the value 1. We need to store the sum and make sure the value is not exceeding 4000000. so we have to create a new variable called $sum initialized with value 0. Create another variable called $c = $a + $b; which holds the sum value of $a and $b.\

Now run a while loop that has a maximum iteration value of 4000000. check if the number is perfectly divisible by 2 then sum the value of $c into $sum and update the value of $a, $b, and $c.