Determine script run time or code execution time

<?php

  $starttime = microtime(true);

   

  // Start Code Excecution

   

  for ($i = 0; $i < 1000000; ++$i) {

    $a = $i;

  }

  // End Code Excecution

   

  $endttime = microtime(true);

   

  $duration = (float)($endttime-$starttime);

  $duration = number_format($duration,2,'.','');

  

  echo $duration." Seconds"; // result somthing like 0.88 Seconds

?>