Problem with DRY

Question

The problem: compare two arrays and give a dot whenever a number of one array is larger than the other. Ex)

A = [1, 2, 2]

B = [2, 1, 1]

result = [2, 1]

The answer I found:

function a($a, $b){

    $a1 = 0;
    $b1 = 0;

    if ($a[0] > $b[0]) {
        $a1++;
    }
    if ($a[1] > $b[1]) {
        $a1++;
    }
    if ($a[2] > $b[2]) {
        $a1++;
    }

    if ($a[0] < $b[0]) {
        $b1++;
    }
    if ($a[1] < $b[1]) {
        $b1++;
    }
    if ($a[2] < $b[2]) {
        $b1++;
    }

return [$a1, $b1];

}

$a = [5,6,7];
$b = [3,6,10];


var_dump(a($a, $b));

But I feel there is a lot of unnecessary repetition in this code. Some enhancement tip?

Answer 1

What you’re doing is walking both arrays at the same time, it is exactly the use case of the for. Using it would not only be repeating less but would also be leaving generic to any size that the arrays have, as long as they are the same size (I did not validate this). The only drawback is that it is slightly slower, but it is derisory and in PHP it makes zero sense to worry about it (in other languages it is almost always also in this case).

function a($a, $b) {
    $a1 = 0;
    $b1 = 0;
    for ($i = 0; $i < count($a); $i++) {
        if ($a[$i] > $b[$i]) $a1++;
        if ($a[$i] < $b[$i]) $b1++;
    }
    return [$a1, $b1];
}
$a = [5, 6, 7];
$b = [3, 6, 10];
var_dump(a($a, $b));

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

You are not violating DRY, you are repeating code, they are different things. I explain this in DRY is to avoid redundancies, right?.

A more basic concern than DRY is to give meaningful names for variables and functions.

Answer 2

I tried a different approach but I think I came to the same result as my colleague:

  $a1 = 0;
  $b1 = 0;


$a = [5,6,7];
$b = [3,6,10];

    $c = count($a);
    for($i = 0; $i < $c;$i++){

        if($a[$i] > $b[$i]){
            $a1++;
        }
        if($a[$i] < $b[$i]){
            $b1++;
        }
    }

echo "a1: " . $a1;
echo "<br>b1: " . $b1;