is_null very slow

I am a newcomer to php; I recently loaded a binary copy (5.0.3) onto my PC
running win2k and Apache 2.0.52.
It seems to work fine except that it is very slow running the function
is_null e.g. the dummy program below -
<?php
for($i=0; $i<1000; $i++) {
if(is_null($x)) $y=0;
}
echo 'done'
?>
This takes around 30 seconds to run and the disk is accessed continuously.
A friend ran it under both win2k and Linux and it finished in under a
second. Have I set up something wrong? As I say everything else seems fine.
Thanks for any help.
Peter Croft

On Wed, 8 Jun 2005 22:11:55 +0100, "Peter Croft"
<peter_croft@textandvideo.co.uk> wrote:
[color=blue]
>I am a newcomer to php; I recently loaded a binary copy (5.0.3) onto my PC
>running win2k and Apache 2.0.52.
>It seems to work fine except that it is very slow running the function
>is_null e.g. the dummy program below -
><?php
>for($i=0; $i<1000; $i++) {
> if(is_null($x)) $y=0;
> }
>echo 'done'
>?>
>This takes around 30 seconds to run and the disk is accessed continuously.
>A friend ran it under both win2k and Linux and it finished in under a
>second. Have I set up something wrong? As I say everything else seems fine.[/color]

That would produce 1000 warnings under a sensible error_reporting
configuration.

Perhaps your copy is logging warnings to a file, whereas your friend's has
error reporting disabled entirely.

--
Andy Hassall / <andy@andyh.co.uk> / <http://www.andyh.co.uk>
<http://www.andyhsoftware.co.uk/space> Space: disk usage analysis tool

Thanks - that seems to be the answer.
I see I misunderstood is_null. What I was trying to do was to find which
values in an array had not been assigned to
and then give them a value
(It is more convenient for me to do things this way than to assign default
values to start with.)
e.g.
$x[0]=1;
$x[101]=22;
for($i=0; $i<1000; $i++) {
if(is_null($x[$i])) $x[$i]=$i;
}
I have just read about isset - is that the right way to do it?
To a php-newbie it seems a bit strange that some elements in an array can be
considered undefined whilst others aren't.
Cheers,
Peter



"Andy Hassall" <andy@andyh.co.uk> wrote in message
news:08oea15ohcgacho64ngn45e06kg1vpouv2@4ax.com...[color=blue]
> On Wed, 8 Jun 2005 22:11:55 +0100, "Peter Croft"
> <peter_croft@textandvideo.co.uk> wrote:
>[color=green]
> >I am a newcomer to php; I recently loaded a binary copy (5.0.3) onto my[/color][/color]
PC[color=blue][color=green]
> >running win2k and Apache 2.0.52.
> >It seems to work fine except that it is very slow running the function
> >is_null e.g. the dummy program below -
> ><?php
> >for($i=0; $i<1000; $i++) {
> > if(is_null($x)) $y=0;
> > }
> >echo 'done'
> >?>
> >This takes around 30 seconds to run and the disk is accessed[/color][/color]
continuously.[color=blue][color=green]
> >A friend ran it under both win2k and Linux and it finished in under a
> >second. Have I set up something wrong? As I say everything else seems[/color][/color]
fine.[color=blue]
>
> That would produce 1000 warnings under a sensible error_reporting
> configuration.
>
> Perhaps your copy is logging warnings to a file, whereas your friend's[/color]
has[color=blue]
> error reporting disabled entirely.
>
> --
> Andy Hassall / <andy@andyh.co.uk> / <http://www.andyh.co.uk>
> <http://www.andyhsoftware.co.uk/space> Space: disk usage analysis tool[/color]

Following on from Peter Croft's message. . .[color=blue]
>To a php-newbie it seems a bit strange that some elements in an array can be
>considered undefined whilst others aren't.[/color]

You often find empty building plots in a street.

Some houses are vacant. - $house[67]=0;

Some may not be built or have been demolished.
- unset($house[45])


--
PETER FOX Not the same since the e-commerce business came to a .
peterfox@eminent.demon.co.uk.not.this.bit.no.html
2 Tees Close, Witham, Essex.
Gravity beer in Essex <http://www.eminent.demon.co.uk>

Why don't you use isset() or empty() instead then?