regex_trim.php

<?php
function benchmark($title, $loop = 1, callable $target)
{
    echo '# ' . $title, PHP_EOL;
    $start = microtime(true);
    for ($i = 0; $i < $loop; $i++) {
        $target();
    }
    echo (microtime(true) - $start) / $loop, PHP_EOL;
    echo PHP_EOL;
}

function benchmark_loop($title, callable $target)
{
    foreach ([20, 200, 2000, 20000, 200000] as $no) {
        $string = str_repeat(' ', $no) . 'a';
        benchmark($title . ' - ' . $no, 3, function () use ($string, $target) {
            return $target($string);
        });
    }
}

benchmark_loop('\s+$', function ($string) {
    return preg_replace('/\s+$/', '', $string);
});

benchmark_loop('\s++$', function ($string) {
    return preg_replace('/\s++$/', '', $string);
});

benchmark_loop('rtrim', function ($string) {
    return rtrim($string);
});