stopwatch.php

<?php
function stopwatch($str = null)
{
    static $time = null;
    if (is_null($str)) {
        $time = microtime(true);
    } else {
        echo $str . ( microtime(true) - $time) . "sec" . PHP_EOL;
        $time = 0;
    }
}

stopwatch();
sleep(1);
stopwatch();