measuring the elapsed time between code segments in PHP

Question

From time time to time, I\'d like to be able to measure the elapsed time between two segments of code. This is solely to be able to detect the bottlenecks within the code an

Answer 1

Same drew010 function (thanks!), only added custom comment and time displays in microseconds (us):

    function time_elapsed($comment) 
        {

        static $time_elapsed_last = null;
        static $time_elapsed_start = null;

        // $unit="s"; $scale=1000000; // output in seconds
        // $unit="ms"; $scale=1000; // output in milliseconds
        $unit="μs"; $scale=1; // output in microseconds

        $now = microtime(true);

        if ($time_elapsed_last != null) {
            echo "\n";
            echo '";
            echo "\n";
        } else {
            $time_elapsed_start=$now;
        }

        $time_elapsed_last = $now;
    }               

Example:

// Start timer
time_elapsed('');

// Do something
usleep(100);
time_elapsed('Now awake, sleep again');

// Do something
usleep(100);
time_elapsed('Game over');

Ouput: