Performance of null checking

check_for_null.php

<?php

define('DEFAULT_ITERATIONS', 1000000);
$myNull = null;

$options = getopt('n:');

$iterations = isset($options['n']) ? intval($options['n']) : DEFAULT_ITERATIONS;

logLine('iterations = ' . $iterations);

logLine('>>> Checking `is_null`');
$startTime = lap();
for ($i = 0; $i < $iterations; $i++) {
  if (is_null($myNull)) {
    continue;
  }
}
$endTime = lap();
logDuration($startTime, $endTime);

logLine('>>> Checking `null !== `');
$startTime = lap();
for ($i = 0; $i < $iterations; $i++) {
  if (null !== $myNull) {
    continue;
  }
}
$endTime = lap();
logDuration($startTime, $endTime);

function lap() {
  return microtime(true);
}

function logDuration($start, $end) {
  $duration = $end - $start;
  $message = sprintf('Duration: %f', $duration);
  logLine($message);
}

function logLine($message) {
  echo $message . PHP_EOL;
}

php check_for_null.php -n 5

iterations = 5
>>> Checking `is_null`
Duration: 0.000007
>>> Checking `null !== `
Duration: 0.000004

php check_for_null.php -n 5000000

iterations = 5000000
>>> Checking `is_null`
Duration: 0.089797
>>> Checking `null !== `
Duration: 0.085138