我想知道执行一个PHP for循环需要多少毫秒。

我知道一个泛型算法的结构,但不知道如何在PHP中实现它:

Begin
init1 = timer(); // where timer() is the amount of milliseconds from midnight
the loop begin
some code
the loop end
total = timer() - init1;
End

当前回答

你可以通过以下方式使用微时间(true):

把这个放在你的php文件的开头:

//place this before any script you want to calculate time
$time_start = microtime(true);

//你的脚本代码在这里

// do something

把这个放在你的php文件的末尾:

// Display Script End time
$time_end = microtime(true);

//dividing with 60 will give the execution time in minutes other wise seconds
$execution_time = ($time_end - $time_start)/60;

//execution time of the script
echo '<b>Total Execution Time:</b> '.$execution_time.' Mins';

它将在几分钟内输出结果。

其他回答

您可以用一个函数找到以秒为单位的执行时间。

// ampersand is important thing here
function microSec( & $ms ) {
    if (\floatval( $ms ) == 0) {
        $ms = microtime( true );
    }
    else {
        $originalMs = $ms;
        $ms = 0;
        return microtime( true ) - $originalMs;
    }
}

// you don't have to define $ms variable. just function needs
// it to calculate the difference.
microSec($ms);
sleep(10);
echo microSec($ms) . " seconds"; // 10 seconds

for( $i = 0; $i < 10; $i++) {
    // you can use same variable everytime without assign a value
    microSec($ms);
    sleep(1);
    echo microSec($ms) . " seconds"; // 1 second
}

for( $i = 0; $i < 10; $i++) {
    // also you can use temp or useless variables
    microSec($xyzabc);
    sleep(1);
    echo microSec($xyzabc) . " seconds"; // 1 second
}

你可以通过以下方式使用微时间(true):

把这个放在你的php文件的开头:

//place this before any script you want to calculate time
$time_start = microtime(true);

//你的脚本代码在这里

// do something

把这个放在你的php文件的末尾:

// Display Script End time
$time_end = microtime(true);

//dividing with 60 will give the execution time in minutes other wise seconds
$execution_time = ($time_end - $time_start)/60;

//execution time of the script
echo '<b>Total Execution Time:</b> '.$execution_time.' Mins';

它将在几分钟内输出结果。

下面是一个返回小数秒的实现(即1.321秒)

/**
 * MICROSECOND STOPWATCH FOR PHP
 *
 * Class FnxStopwatch
 */
class FnxStopwatch
{
    /** @var float */
    private $start,
            $stop;

    public function start()
    {
        $this->start = self::microtime_float();
    }
    public function stop()
    {
        $this->stop = self::microtime_float();
    }
    public function getIntervalSeconds() : float
    {
        // NOT STARTED
        if (empty($this->start))
            return 0;
        // NOT STOPPED
        if (empty($this->stop))
            return ($this->stop - self::microtime_float());

        return $interval = $this->stop - $this->start;
    }

    /**
     * FOR MORE INFO SEE http://us.php.net/microtime
     *
     * @return float
     */
    private static function microtime_float() : float
    {
        list($usec, $sec) = explode(" ", microtime());

        return ((float)$usec + (float)$sec);
    }
}
<?php
// Randomize sleeping time
usleep(mt_rand(100, 10000));

// 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";
?>

这是这个的链接

你可以使用微时间功能。从文档中可以看到:

microtime -以微秒为单位返回当前Unix时间戳 如果get_as_float被设置为TRUE,则microtime()返回一个浮点数,它表示当前时间(以秒为单位),从Unix纪元开始精确到最近的微秒。

使用示例:

$start = microtime(true);
while (...) {

}
$time_elapsed_secs = microtime(true) - $start;