还有其他方法可以做到这一点吗？因为$timestart和$timestop都会给我相同的结果，即使两者之间有一个事件。
<?php
$timestart = strtotime(date('H:i:s', time()));
if(isset($_POST['choix186']) ){
$timestop = strtotime(date('H:i:s', time()));
$duree = $timestop - $timestart;
}
print $duree";
?>
"标准"计时器脚本是这样的：
示例#1使用microtime（）计时脚本执行
$time_start = microtime_float();
// Sleep for a while
usleep(100);
$time_end = microtime_float();
$time = $time_end - $time_start;
echo "Did nothing in $time seconds'n";
?>
示例#2 PHP 5 中定时脚本执行
<?php
$time_start = microtime(true);
// Sleep for a while
usleep(100);
$time_end = microtime(true);
$time = $time_end - $time_start;
echo "Did nothing in $time seconds'n";
?>
示例#3 microtime（）和REQUEST_TIME_FLOAT（从PHP 5.4.0开始）
<?php
// Randomize sleeping time
usleep(mt_rand(100, 10000));
// As of PHP 5.4.0, REQUEST_TIME_FLOAT is available in the $_SERVER superglobal array.
// It contains the timestamp of the start of the request with microsecond precision.
$time = microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];
echo "Did nothing in $time seconds'n";
?>
来源：http://php.net/manual/en/function.microtime.php
无需添加，手动了解所有