PHP microtime function

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microtime

(PHP 3, PHP 4, PHP 5)

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.

If the optional get_as_float is set to
TRUE then a float (in seconds) is returned.

Example 1. Timing script execution with microtime()

/**
 * 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\n";

Example 2. Timing script execution in PHP 5

$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";