gettimeofday

说明

mixed gettimeofday ( [bool return_float] )

本函数是 gettimeofday(2) 的接口。返回一个关联数组，包含有系统调用返回的数据。

自 PHP 5.1.0 起有个可选参数 return_float，当其设为 TRUE 时，gettimeofday() 会返回一个浮点数。

数组中的键为：

"sec" - 自 Unix 纪元起的秒数
"usec" - 微秒数
"minuteswest" - 格林威治向西的分钟数
"dsttime" - 夏令时修正的类型

例子 1. gettimeofday() example
<?php print_r(gettimeofday()); echo gettimeofday(true); ?>
上例的输出类似于：
Array ( [sec] => 1073504408 [usec] => 238215 [minuteswest] => 0 [dsttime] => 1 ) 1073504408.23910

add a note User Contributed Notes

void0( the dog )yandex.ru
21-Sep-2006 02:07


do you realy think that convertion to String and back to float can be fast??

this function runs 10 times faster than utime() :



function fastUtime()

{

  $t = gettimeofday();

  return (float) ($t['sec'] + $t['usec'] / 1000000.0);

}

lucas dot karisny at linuxmail dot org
14-Feb-2005 10:26


A small improvement on getTimer.  Using vsprintf instead of sprintf there is no need to assign the array:



<?php

function utime()

{

  return (float) (vsprintf('%d.%06d', gettimeofday()));

}

?>



In a test on my machine getTimer took 0.037519 seconds to run through 1000 iterations versus 0.027912 seconds for utime.  In total, utime runs about 25% quicker.  The use is negligible in an actual benchmarking scenario, but this could provide a slightly more accurate estimate.  Of course the time it takes to run the function could always be stored at the start and subtracted from your total value each time it is run.

beidson at calpoly dot edu
14-Sep-2000 02:21


Since USLEEP doesn't work under windows, you need to come up with your own fix. gettimeofday() can access useconds on a windows box, so this little function using gettimeofday() will do the trick. 





function wait($usecs){ 


 $temp=gettimeofday(); 


 $start=(int)$temp["usec"]; 


 while(1){ 


  $temp=gettimeofday(); 


  $stop=(int)$temp["usec"]; 


  if ($stop-$start >= $usecs) break; 


 } 


} 





The smallest amount of time it seems to work with is around 200usecs, but if you wait() anything higher than 200usecs it's pretty close.

middleto at pilot dot msu dot edu
13-Aug-1999 10:49


The types of DST correction (from sys/time.h on a Linux system):


 0     Not on DST


 1     USA DST


 2     Austrailian DST


 3     Western European DST


 4     Middle European DST


 5     Eastern European DST


 6     Canada DST


 7     Great Britain and Eire DST


 8     Rumania DST


 9     Turkey


10     Australian DST (with shift in 1986)

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