How to determine the memory footprint (size) of a variable?

Question

Is there a function in PHP (or a PHP extension) to find out how much memory a given variable uses? sizeof just tells me the number of elements/properties.

Answer 1

You could opt for calculating memory difference on a callback return value. It's a more elegant solution available in PHP 5.3+.

function calculateFootprint($callback) {
    $startMemory = memory_get_usage();
    $result = call_user_func($callback);
    return memory_get_usage() - $startMemory;
}

$memoryFootprint = calculateFootprint(
    function() {
        return range(1, 1000000);
    }
);

echo ($memoryFootprint / (1024 * 1024)) . ' MB' . PHP_EOL;