Question

I’ve tried Google, php.net and the php mailinglist’s archives, but I can’t find
what I’m looking for. Maybe it’s obvious, or maybe nobody wonders about
this…

For years, I’ve used microtime() to get the current time including the
microseconds. However, somebody pointed me at a sentence in the manual
page: “This function is only available on operating systems that support
the gettimeofday() system call.”

And PHP’s gettimeofday() suggests the same situation: “This is an
interface to gettimeofday(2).”

But… what kind of systems then don’t have this system call available?
Some googling around provided lots of C programmers trying to get a
gettimeofday() implementation in C on Windows, since it doesn’t seem to
include it. But PHP’s microtime() and gettimeofday() seem to work just
fine on Windows (at least the boxes I could get to). Also, I just can’t
seem to find PHP code anywhere on the web that seems to check the
existence of either microtime() or gettimeofday() before they call it,
and there have to be lots of PHP programmers out there working on
Windows boxes so…

Should I ignore the sentence in the manual and just trust that both
functions are always available? Or is there another cross-platform way
to get to the system time, including the microseconds, without using
microtime() or gettimeofday()? Or will both functions just always exist,
but just not give me microseconds if there is no gettimeofday() system
call available?

EDIT 1:

http://www.php.net/microtime

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

Maybe this clarifies my point somewhat.

Answer 1

According to sources PHP has its own gettimeofday implementation for Windows. But there’s no other ports of gettimeofday available. So except UNIX based systems and Windows, any other operating systems cannot use microtime()