经测试代码如下：
/**
* 计算执行时间
*
* @param
* @author 编程之家 jb51.cc jb51.cc
**/
$time_start = microtime(true);
$time_end = microtime(true);
$time = $time_end - $time_start;
echo 'Script took '.$time.' seconds to execute';
/*** 代码来自编程之家 jb51.cc（jb51.cc） ***/