How to subtract microtime and display date with milliseconds in php?

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How to subtract microtime and display date with milliseconds in php? – Here in this article, we will share some of the most common and frequently asked about PHP problem in programming with detailed answers and code samples. There’s nothing quite so frustrating as being faced with PHP errors and being unable to figure out what is preventing your website from functioning as it should like php and microtime . If you have an existing PHP-based website or application that is experiencing performance issues, let’s get thinking about How to subtract microtime and display date with milliseconds in php?.

How to subtract microtime and display date with milliseconds in php ?

For example: I have set end date and time

$endtime = 2012-02-21 10:29:59;

then I have current date or start date with converted from microtime

$starttime = 2012-02-21 10:27:59.452;

function getTimestamp()
{
        $microtime = floatval(substr((string)microtime(), 1, 8));
        $rounded = round($microtime, 3);
        return date("Y-m-d H:i:s") . substr((string)$rounded, 1, strlen($rounded));
}

echo getTimestamp(); //sample output 2012-02-21 10:27:59.452

Now I want to subtract:
$finaldate = $endtime – $starttime;

I want my output to be like this: 00:00:02.452

Solution :

You need to use microtime for the start/end values, and only format it for display at the end.

// Get the start time in microseconds, as a float value
$starttime = microtime(true);

/************/
/* Do stuff */
/************/

// Get the difference between start and end in microseconds, as a float value
$diff = microtime(true) - $starttime;

// Break the difference into seconds and microseconds
$sec = intval($diff);
$micro = $diff - $sec;

// Format the result as you want it
// $final will contain something like "00:00:02.452"
$final = strftime('%T', mktime(0, 0, $sec)) . str_replace('0.', '.', sprintf('%.3f', $micro));

Note: this is returning float values from microtime and using float arithmetic to simplify the math, so your numbers may be extremely slightly off due to the float rounding problem, but you are rounding the result to 3 digits in the end anyway, and minor fluctuations in processor timing are greater than floating point errors anyway, so this is not problem for you on multiple levels.

Well phpmyadmin uses this a code like this to calculate the time that a query took. It’s similar to your requirements:

//time before
list($usec, $sec) = explode(' ',microtime($starttime));
$querytime_before = ((float)$usec + (float)$sec);
/* your code */

//time after
list($usec, $sec) = explode(' ',microtime($endtime));
$querytime_after = ((float)$usec + (float)$sec);
$querytime = $querytime_after - $querytime_before;

I think this should work for you. You just have to figure your output format

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