php man page for microtime

MICROTIME(3)								 1							      MICROTIME(3)

microtime - Return current Unix timestamp with microseconds

SYNOPSIS
       mixed microtime ([bool  $get_as_float = false])

DESCRIPTION
       microtime(3)  returns  the  current Unix timestamp with microseconds. This function is only available on operating systems that support the
       gettimeofday() system call.

PARAMETERS
	      o $get_as_float
		- If used and set to TRUE, microtime(3) will return a float instead of a string, as described in the return values section below.

RETURN VALUES
	By default, microtime(3) returns a string in the form "msec sec", where sec is the number of seconds since the Unix epoch (0:00:00 January
       1,1970 GMT), and msec measures microseconds that have elapsed since sec and is also expressed in seconds.

	If  $get_as_float  is  set  to	TRUE, then microtime(3) returns a float, which represents the current time in seconds since the Unix epoch
       accurate to the nearest microsecond.

EXAMPLES
       Example #1

	      Timing script execution with microtime(3)

	      <?php
	      /**
	       * Simple function to replicate PHP 5 behaviour
	       */
	      function microtime_float()
	      {
		  list($usec, $sec) = explode(" ", microtime());
		  return ((float)$usec + (float)$sec);
	      }

	      $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
";
	      ?>

       Example #2

	      Timing script execution in PHP 5

	      <?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
";
	      ?>

       Example #3

	      microtime(3) and REQUEST_TIME_FLOAT (as of PHP 5.4.0)

	      <?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
";
	      ?>

SEE ALSO
       time(3).

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