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

I had a similar problem, and the solution I used was to write the variable to a file then run filesize() on it. Roughly like this (untested code):

function getVariableSize ( $foo ) 
{
    $tmpfile = "temp-" . microtime(true) . ".txt";
    file_put_contents($tmpfile, $foo);
    $size = filesize($tmpfile);
    unlink($tmpfile);
    return $size;
}

This solution isn't terribly fast because it involves disk IO, but it should give you something much more exact than the memory_get_usage tricks. It just depends upon how much precision you require.