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# microtime

(PHP 3, PHP 4 , PHP 5)

microtime -- Return current Unix timestamp with microseconds

## Description

mixed microtime ( [bool get_as_float])

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

When called without the optional argument, this function returns the string "msec sec" where sec is the current time measured in the number of seconds since the Unix Epoch (0:00:00 January 1, 1970 GMT), and msec is the microseconds part. Both portions of the string are returned in units of seconds.

When get_as_float is given, and evaluates to `TRUE`, microtime() will return a float.

> 備注: The get_as_float parameter was added as of PHP 5.0.0.

示範 1.Timing script execution with microtime()
`<?php /** * Simple function to replicate PHP5 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\n"; ?>`

示範 2.Timing script execution in PHP5
`<?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\n"; ?>`

See also time().

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