Hi Yasuo,
Thanks for taking the trouble to explain everything in such detail.
Actually I understood your first message. What it doesn't explain is why:
$gGlobal == 1 is changed permanently to $gGlobal == 55.
in the following code:
<?php
function ChangeGlobalValue()
{
global $gGlobal;
$local = 55;
$gGlobal = $local;
print "Value:Global=$gGlobal<BR>";
}
$gGlobal = 1;
ChangeGlobalValue();
print $gGlobal; <=============== THIS IS 55 NOW
?>
==========================
""Yasuo Ohgaki"" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> ----- Original Message -----
> From: "John" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, March 16, 2001 9:12 PM
> Subject: Re: [PHP] Strange PHP Reference behaviour with globals
>
>
> > Thanks Yasuo,
> >
> > That might explain why $gGlobal is not permanently set to 99,
> > but that doesn't explain why $gGlobal is set to 55 in
ChangeGlobalValue()
> > permanently. So are you or am I missing something?
>
> Reference in PHP is not actually a pointer. It's a common pithole for
C/C++
> programmers.
> In C/C++, you will get 99, instead of 55. But we get 55 in PHP. Here is
why.
>
> Reference is just a place holder for a value.
>
> Your code creates referece with "global" statement asI wrote in previous
mail.
>
> global $var;
>
> creates reference to $GLOBAL['var'] for local $var IN function scope.
>
> $var is actually a reference, NOT a variable itself nor a pointer.
>
> > > > function ChangeGlobalRef()
> > > > {
> > > > global $gGlobal;
>
> Creating reference here, for $GLOBAL['gGlobal'].
>
> > > >
> > > > $local = 99;
> > > > $gGlobal = &$local;
>
> You assign reference of "$local" to "$gGlobal" which is also a reference.
>
> $gGlobal = &$local;
>
> This replaces $gGlobal(reference) with $local(reference).
> Your code does not change $GLOBAL['gGlobal'], which is the value you want
to
> change.
>
> > > > print "Ref:Global=$gGlobal<BR>";
> > > > }
>
> Since your code replace reference with reference inside function scope.
> You get $gGlobal = 99 inside the function, but not outside the function.
> (Note: Your $gGlobal is refered to $local that has 99 in the function)
> Because $gGlobal itself is local to the function.
>
> Therefore, you cannot get 99 outside the function, but 55.
>
> I hope I explained well, so that all readers understand what I'm talking
about.
>
> Regards,
> --
> Yasuo Ohgaki
>
> > Bye, John
> >
> > ""Yasuo Ohgaki"" <[EMAIL PROTECTED]> wrote in message
> > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > This is expected behavior of PHP's reference. Reference works like a
> > pointer,
> > > but it dose NOT works like a pointer. This is case that reference
does
> > not
> > > works as many programmer expected.
> > >
> > > I think this is in manual.
> > >
> > > Hint: when programmer use 'global $var'. It is the same as do '$var =
&
> > > $GLOBALS['var']'.
> > >
> > > Regards,
> > >
> > > Yasuo Ohgaki
> > > =========================
> > > My favorite links
> > > [RFC] http://www.faqs.org/rfcs/ [W3C] http://www.w3.org/
> > > [PHP Manual] http://www.php.net/manual/en/
> > >
> > > > Hello,
> > > >
> > > > Try the following code:
> > > >
> > > > <?php
> > > >
> > > > $gGlobal = 1;
> > > > function ChangeGlobalValue()
> > > > {
> > > > global $gGlobal;
> > > >
> > > > $local = 55;
> > > > $gGlobal = $local;
> > > > print "Value:Global=$gGlobal<BR>";
> > > > }
> > > >
> > > > function ChangeGlobalRef()
> > > > {
> > > > global $gGlobal;
> > > >
> > > > $local = 99;
> > > > $gGlobal = &$local;
> > > > print "Ref:Global=$gGlobal<BR>";
> > > > }
> > > >
> > > > print "Global=$gGlobal<BR>";
> > > > ChangeGlobalValue();
> > > > print "Global=$gGlobal<BR>";
> > > > ChangeGlobalRef();
> > > > print "Global=$gGlobal<BR>";
> > > > ?>
> > > >
> > > > I get the following results:
> > > >
> > > > Global=1
> > > > Value:Global=55
> > > > Global=55
> > > > Ref:Global=99
> > > > Global=55 <=========== shouldn't this be 99 ???
> > > >
> > > > Why does setting a global variable to a reference fail in a
function?
> > > >
> > > > Tested on PHP 4.0.4 on IIS5 (CGI version).
> > > >
> > > >
> > > >
> > > >
> > > > --
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> > > >
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