Re: [PHP] in_array() related problem
Hi,
Thanks for your reply. After a sleep overnight I found I said
something really stupid. Arrays are compared in deep, and also for
objects. I really forgot the old PHP4 way and thought PHP5 compares
object simply by address when using ==, which is not the real case. I
need to use === for comparing objects of the same instance. And thanks
Tom for pointing out to use the strict parameter.
On 11/4/06, Richard Lynch <[EMAIL PROTECTED]> wrote:
> Try providing a custom comparison function.
>
> Almost for sure, PHP is attempting to "test" the == by a deeper scan
> than you think.
>
> On Fri, November 3, 2006 10:56 am, tamcy wrote:
> > Hello all,
> >
> > I'm new to this list. To not flooding the bug tracking system I hope
> > to clarify some of my understanding here.
> >
> > I am referring to the (now bogus) bug report
> > http://bugs.php.net/bug.php?id=39356&edit=2. This happens after my
> > upgrade to PHP 5.2, where the code shown produces a "Fatal error:
> > Nesting level too deep - recursive dependency?". Same testing code
> > reproduced below:
> >
> >
> > > class A
> > {
> > public $b;
> > }
> >
> > class B
> > {
> > public $a;
> > }
> >
> > $a = new A;
> > $b = new B;
> > $b->a = $a;
> > $a->b = $b;
> >
> > $test = array($a, $b);
> >
> > var_dump(in_array($a, $test));
> >
> >
> > I think this is not rare for a child item to have knowledge about its
> > parent, forming a cross-reference.
> >
> > This code runs with no problem in PHP5.1.6, but not in 5.2. Ilia
> > kindly points out that "In php 5 objects are passed by reference, so
> > your code does in
> > fact create a circular dependency.". I know the passed by reference
> > rule. What I'm now puzzled is, why this should lead to an error.
> >
> > To my knowledge, despite the type-casting issue and actual algorithm,
> > in_array() should actually do nothing more than:
> >
> > function mimic_in_array($search, $list)
> > {
> > foreach ($list as $item)
> > if ($search == $item)
> > return true;
> > return false;
> > }
> >
> > Which means:
> > 1. in_array() isn't multi-dimensional.
> > 2. in_array() doesn't care about the properties of any object.
> >
> > That is, I don't expect in_array() to nest through all available inner
> > arrays for a match, not to mention those are object properties, not
> > arrays.
> >
> > So here is the question: Why should in_array() throws such a "Fatal
> > error: Nesting level too deep" error? Why should it care? Is there any
> > behaviour I don't know?
> >
> > Thanks all in advance.
> >
> > Tamcy
> >
> > --
> > PHP General Mailing List (http://www.php.net/)
> > To unsubscribe, visit: http://www.php.net/unsub.php
> >
> >
>
>
> --
> Some people have a "gift" link here.
> Know what I want?
> I want you to buy a CD from some starving artist.
> http://cdbaby.com/browse/from/lynch
> Yeah, I get a buck. So?
>
>
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Re: [PHP] in_array() related problem
Try like this:
var_dump(in_array($a, $test, true));
Richard Lynch wrote:
Try providing a custom comparison function.
Almost for sure, PHP is attempting to "test" the == by a deeper scan
than you think.
On Fri, November 3, 2006 10:56 am, tamcy wrote:
Hello all,
I'm new to this list. To not flooding the bug tracking system I hope
to clarify some of my understanding here.
I am referring to the (now bogus) bug report
http://bugs.php.net/bug.php?id=39356&edit=2. This happens after my
upgrade to PHP 5.2, where the code shown produces a "Fatal error:
Nesting level too deep - recursive dependency?". Same testing code
reproduced below:
a = $a;
$a->b = $b;
$test = array($a, $b);
var_dump(in_array($a, $test));
I think this is not rare for a child item to have knowledge about its
parent, forming a cross-reference.
This code runs with no problem in PHP5.1.6, but not in 5.2. Ilia
kindly points out that "In php 5 objects are passed by reference, so
your code does in
fact create a circular dependency.". I know the passed by reference
rule. What I'm now puzzled is, why this should lead to an error.
To my knowledge, despite the type-casting issue and actual algorithm,
in_array() should actually do nothing more than:
function mimic_in_array($search, $list)
{
foreach ($list as $item)
if ($search == $item)
return true;
return false;
}
Which means:
1. in_array() isn't multi-dimensional.
2. in_array() doesn't care about the properties of any object.
That is, I don't expect in_array() to nest through all available inner
arrays for a match, not to mention those are object properties, not
arrays.
So here is the question: Why should in_array() throws such a "Fatal
error: Nesting level too deep" error? Why should it care? Is there any
behaviour I don't know?
Thanks all in advance.
Tamcy
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] in_array() related problem
Try providing a custom comparison function.
Almost for sure, PHP is attempting to "test" the == by a deeper scan
than you think.
On Fri, November 3, 2006 10:56 am, tamcy wrote:
> Hello all,
>
> I'm new to this list. To not flooding the bug tracking system I hope
> to clarify some of my understanding here.
>
> I am referring to the (now bogus) bug report
> http://bugs.php.net/bug.php?id=39356&edit=2. This happens after my
> upgrade to PHP 5.2, where the code shown produces a "Fatal error:
> Nesting level too deep - recursive dependency?". Same testing code
> reproduced below:
>
>
> class A
> {
> public $b;
> }
>
> class B
> {
> public $a;
> }
>
> $a = new A;
> $b = new B;
> $b->a = $a;
> $a->b = $b;
>
> $test = array($a, $b);
>
> var_dump(in_array($a, $test));
>
>
> I think this is not rare for a child item to have knowledge about its
> parent, forming a cross-reference.
>
> This code runs with no problem in PHP5.1.6, but not in 5.2. Ilia
> kindly points out that "In php 5 objects are passed by reference, so
> your code does in
> fact create a circular dependency.". I know the passed by reference
> rule. What I'm now puzzled is, why this should lead to an error.
>
> To my knowledge, despite the type-casting issue and actual algorithm,
> in_array() should actually do nothing more than:
>
> function mimic_in_array($search, $list)
> {
> foreach ($list as $item)
> if ($search == $item)
> return true;
> return false;
> }
>
> Which means:
> 1. in_array() isn't multi-dimensional.
> 2. in_array() doesn't care about the properties of any object.
>
> That is, I don't expect in_array() to nest through all available inner
> arrays for a match, not to mention those are object properties, not
> arrays.
>
> So here is the question: Why should in_array() throws such a "Fatal
> error: Nesting level too deep" error? Why should it care? Is there any
> behaviour I don't know?
>
> Thanks all in advance.
>
> Tamcy
>
> --
> PHP General Mailing List (http://www.php.net/)
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>
--
Some people have a "gift" link here.
Know what I want?
I want you to buy a CD from some starving artist.
http://cdbaby.com/browse/from/lynch
Yeah, I get a buck. So?
--
PHP General Mailing List (http://www.php.net/)
To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] in_array() related problem
Hello all,
I'm new to this list. To not flooding the bug tracking system I hope
to clarify some of my understanding here.
I am referring to the (now bogus) bug report
http://bugs.php.net/bug.php?id=39356&edit=2. This happens after my
upgrade to PHP 5.2, where the code shown produces a "Fatal error:
Nesting level too deep - recursive dependency?". Same testing code
reproduced below:
a = $a;
$a->b = $b;
$test = array($a, $b);
var_dump(in_array($a, $test));
I think this is not rare for a child item to have knowledge about its
parent, forming a cross-reference.
This code runs with no problem in PHP5.1.6, but not in 5.2. Ilia
kindly points out that "In php 5 objects are passed by reference, so
your code does in
fact create a circular dependency.". I know the passed by reference
rule. What I'm now puzzled is, why this should lead to an error.
To my knowledge, despite the type-casting issue and actual algorithm,
in_array() should actually do nothing more than:
function mimic_in_array($search, $list)
{
foreach ($list as $item)
if ($search == $item)
return true;
return false;
}
Which means:
1. in_array() isn't multi-dimensional.
2. in_array() doesn't care about the properties of any object.
That is, I don't expect in_array() to nest through all available inner
arrays for a match, not to mention those are object properties, not
arrays.
So here is the question: Why should in_array() throws such a "Fatal
error: Nesting level too deep" error? Why should it care? Is there any
behaviour I don't know?
Thanks all in advance.
Tamcy
--
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