"php array performance" Answer’s

0

Array access in PHP can certainly be slow. PHP uses hash tables to implement arrays, i.e. in order to access an element in an array it has to calculate a hash and traverse a linked list. Using a compiled language with real arrays will definitely improve performance, because there a direct memory access is made. For the interested: Code for hash access with string and with integer.

Concerning your code, there are several points I would optimize:

  • return directly, don't break twice.
  • put $file->get_width() and $file->get_height into simple variables. I assume that the height or width doesn't change throughout the process. Remember: Functions in PHP are slow.
  • Use a one-dimensional array, instead of nested arrays. You save one hash lookup per iteration that way. Actually a one-dimensional array is only marginally faster or even slightly slower. Comparison of several ways of saving the data concerning performance and memory usage.

.

function fits($bin, $x, $y, $w, $h) {
    $w += $x;
    $h += $y;

    for ($i = $x; $i < $w; ++$i) {
        for ($j = $y; $j < $h; ++$j) {
            if ($bin[$i][$j] !== 0) {
                return false;
            }
        } 
    }

    return true;   
}

Though I'm not sure, why you add $x to the $width / $y to the $height. Don't you want to iterate from the current coordinates to the image boundaries?

Wednesday, March 31, 2021
 
DilbertDave
answered 11 Months ago
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