Sometimes I want a quick and simple way to know how long a block of code took to run. The usual way you see it done is something like this:

$startTime = microtime(true);

// Code to test

$endTime = microtime(true);
$time = $endTime - $startTime;

$time contains the number of seconds which it took for the code to run.

There is a simpler way:

$time = -microtime(true);

// Code to test

$time += microtime(true);

This automatically calculates the difference between start and end without needing the extra step.

The same cane be done for memory usage:

$memory = -memory_get_usage();

// Code to test

$memory += memory_get_usage();