PHP总结了从0到200的所有偶数

Question

I tried to sum up all even numbers from 0 to 200 and I found 2 possible working ways, however the third method (the most efficient one) gives me a headache. Here's what I did so far:

First method:

$total = 0;
$number = 0;

while ($number < 200)
{
    if ($number % 2 == 0)
    {
        $total = $total + $number;
    }
    $number++;
}

echo $total;

Second method:

    $total = 0;
    for($number = 0; $number < 200; $number+=2) 
    {
        $total += $number;
    }
echo $total;

Third method (can't get it to work)

echo array_sum(range(1,200,2));

How should I change my last method so that it works as intended?

Edit: Seems that none of the methods work: the output should be 10100 but it is 9900 for the first two methods and 10000 for the third.

Answer 1

You need to use

echo array_sum(range(0,198,2));

or

echo array_sum(range(0,199,2));

Its because the above function will sum up the values upto 200 whereas within your while and for loop will count upto 198 only as you have specifically defined

$number < 200