Strange data...

I implemented a timer in my PHP page to see how long it takes to run.
Here's the code:

$this->start_time = microtime();
/* All the code */
$this->end_time = microtime();
$this->calc_time = ($this->end_time - $this->start_time);
print "<tr><td colspan=\"5\">Calculated in: <b>";
printf("%." . $this->time_precision . "f", $this->calc_time);
print " seconds</b></td></tr>\n";

It works, but occasionally it returns a negative value, i.e. -0.890163
seconds. Why does this happen and how can I fix it?

On Fri, 04 Jul 2003 00:54:49 -0700, Zachary Antolak wrote:

> I implemented a timer in my PHP page to see how long it takes to run.
> Here's the code:
>
> $this->start_time = microtime();
> /* All the code */
> $this->end_time = microtime();
> $this->calc_time = ($this->end_time - $this->start_time); print "<tr><td
> colspan=\"5\">Calculated in: <b>"; printf("%." . $this->time_precision .
> "f", $this->calc_time); print " seconds</b></td></tr>\n";
>
> It works, but occasionally it returns a negative value, i.e. -0.890163
> seconds. Why does this happen and how can I fix it?

It's not working reliably because microtime() returns an array, rather
than a single value. One part of the array is the time in seconds, the
other is the decimal places. 0.0015

Use this code to get the microtime as a usable value:

function get_microtime(){
list($micro, $sec) = explode(" ",microtime()); $mtime = (float)$sec +
(float)$micro; return $mtime;
}

Adding the two components together would result in a number 16 digits
long, which is too big for a 'double' or 'float'. PHP seems to throw away
the least significant digits in cases like this, and on my machine the
result appears to be accurate to at least 5 decimal places (1/10,000 s).
---
Posted via news://freenews.netfront.net
Complaints to news@netfront.net

2trax <2trax@salterprojects.com> wrote in message news:<pan.2003.07.04.09.53.42.929205@salterproject s.com>...
> On Fri, 04 Jul 2003 00:54:49 -0700, Zachary Antolak wrote:
>
> > I implemented a timer in my PHP page to see how long it takes to run.
> > Here's the code:
> >
> > $this->start_time = microtime();
> > /* All the code */
> > $this->end_time = microtime();
> > $this->calc_time = ($this->end_time - $this->start_time); print "<tr><td
> > colspan=\"5\">Calculated in: <b>"; printf("%." . $this->time_precision .
> > "f", $this->calc_time); print " seconds</b></td></tr>\n";
> >
> > It works, but occasionally it returns a negative value, i.e. -0.890163
> > seconds. Why does this happen and how can I fix it?
>
> It's not working reliably because microtime() returns an array, rather
> than a single value. One part of the array is the time in seconds, the
> other is the decimal places. 0.0015
>
> Use this code to get the microtime as a usable value:
>
> function get_microtime(){
> list($micro, $sec) = explode(" ",microtime()); $mtime = (float)$sec +
> (float)$micro; return $mtime;
> }
>
> Adding the two components together would result in a number 16 digits
> long, which is too big for a 'double' or 'float'. PHP seems to throw away
> the least significant digits in cases like this, and on my machine the
> result appears to be accurate to at least 5 decimal places (1/10,000 s).
> ---
> Posted via news://freenews.netfront.net
> Complaints to news@netfront.net

Actually, the normal times returned are usually around 0.1xxxxx and
the strange ones are around -0.8xxxxx. They're like a normal value,
but -1. So, I made a test for it:

if ($this->calc_time < 0)
{
$this->calc_time = $this->calc_time + 1;
}

It seems to work. Is this okay to use?