PHP 7.1.12 Released

microtime

(PHP 4, PHP 5, PHP 7)

microtimeRetourne le timestamp UNIX actuel avec les microsecondes

Description

mixed microtime ([ bool $get_as_float = false ] )

microtime() retourne le timestamp Unix, avec les microsecondes. Cette fonction est uniquement disponible sur les systèmes qui supportent la fonction gettimeofday().

Liste de paramètres

get_as_float

Si utilisé et défini à TRUE, microtime() retournera un nombre à virgule flottante au lieu d'une chaîne de caractères, tel que décrit dans la section des valeurs retournées ci-dessous.

Valeurs de retour

Par défaut, microtime() retourne une chaîne de caractères au format "msec sec", où sec est le nombre de secondes depuis l'époque Unix (1 Janvier 1970, 00:00:00 GMT), et msec est le nombre de microsecondes qui se sont écoulées depuis sec, exprimé en secondes.

Si get_as_float est défini à TRUE, alors microtime() retourne un nombre à virgule flottante, qui représente le temps courant, en secondes, depuis l'époque Unix, précis à la microseconde près.

Exemples

Exemple #1 Durée d'exécution d'un script avec la fonction microtime()

<?php
/**
* Fonction simple identique à celle en PHP 5 qui va suivre
*/
function microtime_float()
{
    list(
$usec$sec) = explode(" "microtime());
    return ((float)
$usec + (float)$sec);
}

$time_start microtime_float();

// Attend pendant un moment
usleep(100);

$time_end microtime_float();
$time $time_end $time_start;

echo 
"Ne rien faire pendant $time secondes\n";
?>

Exemple #2 Durée d'exécution d'un script en PHP 5

<?php
$time_start 
microtime(true);

// Attend pendant un moment
usleep(100);

$time_end microtime(true);
$time $time_end $time_start;

echo 
"Ne rien faire pendant $time secondes\n";
?>

Exemple #3 Exemple avec microtime() et REQUEST_TIME_FLOAT (depuis PHP 5.4.0)

<?php
// Durée d'attente aléatoire
usleep(mt_rand(10010000));

// Depuis PHP 5.4.0, REQUEST_TIME_FLOAT est disponible dans le tableau superglobal $_SERVER.
// Il contient le timestamp du début de la requête, avec une précision à la microseconde.
$time microtime(true) - $_SERVER["REQUEST_TIME_FLOAT"];

echo 
"Ne rien faire pendant $time secondes\n";
?>

Voir aussi

  • time() - Retourne le timestamp UNIX actuel

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User Contributed Notes 15 notes

up
128
player27
4 years ago
You can use one variable to check execution $time as follow:

<?php
$time
= -microtime(true);
$hash = 0;
for (
$i=0; $i < rand(1000,4000); ++$i) {
   
$hash ^= md5(substr(str_shuffle("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), 0, rand(1,10)));
}
$time += microtime(true);
echo
"Hash: $hash iterations:$i time: ",sprintf('%f', $time),PHP_EOL;
?>
up
52
Russell G.
4 years ago
Note that the timestamp returned is "with microseconds", not "in microseconds". This is especially good to know if you pass 'true' as the parameter and then calculate the difference between two float values -- the result is already in seconds; it doesn't need to be divided by a million.
up
37
jamie at bishopston dot net
6 years ago
All these timing scripts rely on microtime which relies on gettimebyday(2)

This can be inaccurate on servers that run ntp to syncronise the servers
time.

For timing, you should really use clock_gettime(2) with the
CLOCK_MONOTONIC flag set.

This returns REAL WORLD time, not affected by intentional clock drift.

This may seem a bit picky, but I recently saw a server that's clock was an
hour out, and they'd set it to 'drift' to the correct time (clock is speeded
up until it reaches the correct time)

Those sorts of things can make a real impact.

Any solutions, seeing as php doesn't have a hook into clock_gettime?

More info here: http://tinyurl.com/28vxja9

http://blog.habets.pp.se/2010/09/
gettimeofday-should-never-be-used-to-measure-time
up
20
radek at pinkbike com
12 years ago
A lot of the comments here suggest adding in the following way:  (float)$usec + (float)$sec
Make sure you have the float precision high enough as with the default precision of 12, you are only precise to the 0.01 seconds. 
Set this in you php.ini file.
        precision    =  16
up
11
gomodo at free dot fr
8 years ago
Need a mini benchmark ?
Use microtime with this (very smart) benchmark function :

mixed mini_bench_to(array timelist[, return_array=false])
return a mini bench result

-the timelist first key must be 'start'
-default return a resume string, or array if return_array= true :
'total_time' (ms) in first row
details (purcent) in next row

example :
<?php
unset($t);    // if previous used

//-- zone to bench
$t['start'] = microtime(true);
$tab_test=array(1,2,3,4,5,6,7,8);
$fact=1;
$t['init_values'] = microtime(true);
foreach (
$tab_test as $key=>$value)
{
   
$fact=$fact*$value;
}
$t['loop_fact'] = microtime(true);
echo
"fact = ".$fact."\n";
//-- END zone to bench

echo "---- string result----\n";
$str_result_bench=mini_bench_to($t);
echo
$str_result_bench; // string return
echo "---- tab result----\n";
$tab_result_bench=mini_bench_to($t,true);
echo
var_export($tab_result_bench,true);
?>
this example return:

---- string result----
total time : 0.0141 ms
start -> init_values : 51.1 %
init_values -> loop_fact : 48.9 %
---- tab result----
array (
  'total_time' => 0.0141,
  'start -> init_values' => 51.1,
  'init_values -> loop_fact' => 48.9,
)

The function to include :

<?php
function mini_bench_to($arg_t, $arg_ra=false)
  {
   
$tttime=round((end($arg_t)-$arg_t['start'])*1000,4);
    if (
$arg_ra) $ar_aff['total_time']=$tttime;
    else
$aff="total time : ".$tttime."ms\n";
   
$prv_cle='start';
   
$prv_val=$arg_t['start'];

    foreach (
$arg_t as $cle=>$val)
    {
        if(
$cle!='start')   
        {
           
$prcnt_t=round(((round(($val-$prv_val)*1000,4)/$tttime)*100),1);
            if (
$arg_ra) $ar_aff[$prv_cle.' -> '.$cle]=$prcnt_t;
           
$aff.=$prv_cle.' -> '.$cle.' : '.$prcnt_t." %\n";
           
$prv_val=$val;
           
$prv_cle=$cle;
        }
    }
    if (
$arg_ra) return $ar_aff;
    return
$aff;
  }
?>
up
7
luke at lucanos dot com
9 years ago
Rather than using the list() function, etc. I have found the following code to be a bit cleaner and simpler:
<?php
$theTime
= array_sum( explode( ' ' , microtime() ) );
echo
$theTime;
# Displays "1212018372.3366"
?>
up
3
EdorFaus
11 years ago
Of the methods I've seen here, and thought up myself, to convert microtime() output into a numerical value, the microtime_float() one shown in the documentation proper(using explode,list,float,+) is the slowest in terms of runtime.

I implemented the various methods, ran each in a tight loop 1,000,000 times, and compared runtimes (and output). I did this 10 times to make sure there wasn't a problem of other things putting a load spike on the server. I'll admit I didn't take into account martijn at vanderlee dot com's comments on testing accuracy, but as I figured the looping code etc would be the same, and this was only meant as a relative comparison, it should not be necessary.

The above method took on average 5.7151877 seconds, while a method using substr and simply adding strings with . took on average 3.0144226 seconds. rsalazar at innox dot com dot mx's method using preg_replace used on average 4.1819633 seconds. This shows that there are indeed differences, but for normal use noone is going to notice it.

Note that the substr method mentioned isn't quite the one given anonymously below, but one I made based on it:
<?php
$time
=microtime();
$timeval=substr($time,11).substr($time,1,9);
?>

Also worth noting is that the microtime_float() method gets faster, and no less accurate, if the (float) conversions are taken out and the variables are simply added together.

Any of the methods that used + or array_sum ended up rounding the result to 2 digits after the decimal point, while (most of) the ones using preg_replace or substr and . kept all the digits.

For accurate timing, since floating-point arithmetic would lose precision, I stored microtime results as-is and calculated time difference with this function:
<?php
function microtime_used($before,$after) {
    return (
substr($after,11)-substr($before,11))
        +(
substr($after,0,9)-substr($before,0,9));
}
?>

For further information, the script itself, etc, see http://edorfaus.xepher.net/div/convert-method-test.php
up
4
Robin Leffmann
6 years ago
While doing some experiments on using microtime()'s output for an entropy generator I found that its microsecond value was always quantified to the nearest hundreds (i.e. the number ends with 00), which affected the randomness of the entropy generator. This output pattern was consistent on three separate machines, running OpenBSD, Mac OS X and Windows.

The solution was to instead use gettimeofday()'s output, as its usec value followed no quantifiable pattern on any of the three test platforms.
up
1
Daniel Rhodes
4 years ago
But note that the default 'precision' setting of PHP* - which is used when a float is converted to a stringy format by echo()ing, casting or json_encode()ing etc - is not enough to hold the six digit accuracy of microtime(true).

Out of the box, microtime(true) will echo something like:

1377611450.1234

Which is obviously less than microsecond accuracy. You'll probably want to bump the 'precision' setting up to 16 which will echo something like:

1377611450.123456

*Internally* it will be accurate to the six digits even with the default 'precision', but a lot of things (ie. NoSQL databases) are moving to all-text representations these days so it becomes a bit more important.

* 14 at the time of writing
up
1
Nads
4 years ago
Get date time with milliseconds

$micro_date = microtime();
$date_array = explode(" ",$micro_date);
$date = date("Y-m-d H:i:s",$date_array[1]);
echo "Date: $date:" . $date_array[0];

Test accuracy by running it in a loop.
up
0
johovich at yandex dot ru
19 days ago
//Function to convert microtime return to human readable units
//функция для конвертации времени, принимает значения в секундах

function convert_time($time)
{
    if($time == 0 ){
        return 0;
    }
    //допустимые единицы измерения
    $unit=array(-4=>'ps', -3=>'ns',-2=>'mcs',-1=>'ms',0=>'s');
    //логарифм времени в сек по основанию 1000
    //берем значение не больше 0, т.к. секунды у нас последняя изменяемая по тысяче величина, дальше по 60
    $i=min(0,floor(log($time,1000)));

    //тут делим наше время на число соответствующее единицам измерения т.е. на миллион для секунд,
    //на тысячу для миллисекунд
    $t = @round($time/pow(1000,$i) , 1);
    return $t.$unit[$i];
}
up
0
how to set nonce value with microtime
3 months ago
Using microtime() to set 'nonce' value:

ini_set("precision", 16);
$nonce="nonce=".microtime(true)/0.000001;
up
0
thomas
5 years ago
I have been getting negative values substracting a later microtime(true) call from an earlier microtime(true) call on Windows with PHP 5.3.8

Produces negative values
------------------------------
for($i = 0; $i<100; $i++) {
    $x =  microtime(true);
    //short calculation
    $y = microtime(true);
    echo ($y-$x) . "\n"; // <--- mostly negatives
}

Calling usleep(1) seems to work
---------------------------------------
for($i = 0; $i<100; $i++) {
    $x =  microtime(true);
    //short calculation
    usleep(1);
    $y = microtime(true);
    echo ($y-$x) . "\n"; // <--- fixed now
}
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0
vladson at pc-labs dot info
12 years ago
I like to use bcmath for it
<?php
function micro_time() {
   
$temp = explode(" ", microtime());
    return
bcadd($temp[0], $temp[1], 6);
}

$time_start = micro_time();
sleep(1);
$time_stop = micro_time();

$time_overall = bcsub($time_stop, $time_start, 6);
echo
"Execution time - $time_overall Seconds";
?>
up
-1
langpavel at phpskelet dot org
6 years ago
I use this for measure duration of script execution. This function should be defined (and of couse first call made) as soon as possible.

<?php
/**
* get execution time in seconds at current point of call in seconds
* @return float Execution time at this point of call
*/
function get_execution_time()
{
    static
$microtime_start = null;
    if(
$microtime_start === null)
    {
       
$microtime_start = microtime(true);
        return
0.0;
    }   
    return
microtime(true) - $microtime_start;
}
get_execution_time();

?>

However it is true that result depends of gettimeofday() call. ([jamie at bishopston dot net] wrote this & I can confirm)
If system time change, result of this function can be unpredictable (much greater or less than zero).
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