php实现用于计算执行时间的类实例

<?phpclass c_Timer {var $t_start = 0;var $t_stop = 0;var $t_elapsed = 0;function start() {$this->t_start = microtime();}function stop() {$this->t_stop = microtime();}function elapsed() {if ($this->t_elapsed) {   return $this->t_elapsed;} else {   $start_u = substr($this->t_start,0,10);    $start_s = substr($this->t_start,11,10);   $stop_u = substr($this->t_stop,0,10);     $stop_s = substr($this->t_stop,11,10);   $start_total = doubleval($start_u) + $start_s;   $stop_total = doubleval($stop_u) + $stop_s;   $this->t_elapsed = $stop_total - $start_total;   return $this->t_elapsed;  } }};?>

<?php  $timer = new c_Timer;  $timer->start();  echo "<hr>";  $timer->stop();  echo $timer->elapsed();?>