Array pointer for internal(?) functions

[André Hänsel]

Hi!

This:

function foo()
{
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
while ($a = each(foo()))
{
echo 'dummy';
}

produces an infinite loop. Probably since the result of array_key doesn't
support an array pointer or so, I don't know how this is internally
implemented.

Shouldn't this be considered as a bug? Shouldn't be the resulst of array_key
walkable with each?

Regards,
André

[Chung Leong]

André Hänsel wrote:

Hi!

This:

function foo()
{
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
while ($a = each(foo()))
{
echo 'dummy';
}

produces an infinite loop. Probably since the result of array_key doesn't
support an array pointer or so, I don't know how this is internally
implemented.

Shouldn't this be considered as a bug? Shouldn't be the resulst of array_key
walkable with each?

It's a bug alright--yours. foo() will return a fresh array each time,
so the condition is always true.

[Mladen Gogala]

On Thu, 12 Jan 2006 03:45:30 +0100, André Hänsel wrote:

function foo()
{
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
while ($a = each(foo()))
{
echo 'dummy';
}

Andre, the problem is not in the pointer, the problem is in the
loop. The function foo() will be called each time the loop condition
is checked, producing always a new array and a new set of keys.
Here is a code that does work:
$ cat /tmp/ttt;
<?
function foo() {
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
$b=foo();
while ($a = each($b))
{
echo "dummy\n";
}
?>
$ php /tmp/ttt
dummy
dummy

--
http://www.mgogala.com

[Chung Leong]

André Hänsel wrote:

produces an infinite loop. Probably since the result of array_key doesn't
support an array pointer or so, I don't know how this is internally
implemented.

I should add that there is a real bug in PHP 4.4.1 that causes infinite
loop, shown in the following example.

<?

$array = array(1, 2, 3);

function loop(&$array) {
while(($key = key($array)) !== null) {
echo "Hello $key<br>";
next($array);
}
}

loop($array);

?>

[André Hänsel]

Chung Leong wrote:

André Hänsel wrote:

Hi!

This:

function foo()
{
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
while ($a = each(foo()))
{
echo 'dummy';
}

produces an infinite loop. Probably since the result of array_key
doesn't support an array pointer or so, I don't know how this is
internally implemented.

Shouldn't this be considered as a bug? Shouldn't be the resulst of
array_key walkable with each?

It's a bug alright--yours. foo() will return a fresh array each time,
so the condition is always true.

Oh, I see.

Is there any solution that supports the "while ($a = each(foo()))"
construction?
Caching the result in a static variable?

[Oli Filth]

André Hänsel said the following on 15/01/2006 23:50:

Chung Leong wrote:

André Hänsel wrote:

Hi!

This:

function foo()
{
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
while ($a = each(foo()))
{
echo 'dummy';
}

produces an infinite loop. Probably since the result of array_key
doesn't support an array pointer or so, I don't know how this is
internally implemented.

Shouldn't this be considered as a bug? Shouldn't be the resulst of
array_key walkable with each?

It's a bug alright--yours. foo() will return a fresh array each time,
so the condition is always true.

Oh, I see.

Is there any solution that supports the "while ($a = each(foo()))"
construction?
Caching the result in a static variable?

I guess you could do:

function &foo()
{
static $s = null;
if (null == $s)
{
$a = array('a' => 'b', 'c' => 'd');
$s = array_keys($a);
}
return $s;
}

while ($a = each(foo()))
{
echo 'dummy';
}

Although quite why you would want to do something so perverse, I've no
idea...

You'd be better off writing a custom storage class that implements the
Iterator interface.
--
Oli

[Jim Michaels]

I thought the problem was that each() will return a fresh array each time
because of foo(). each() always adds to the array foo() returns.
I also thought a better solution would be to use a foreach lop instead of
while.
foreach (foo() as $key) {
echo "dummy";
}

"Chung Leong" <ch***********@hotmail.com> wrote in message
news:11*********************@g43g2000cwa.googlegro ups.com...
André Hänsel wrote:

Hi!

This:

function foo()
{
$a = array('a' => 'b', 'c' => 'd');
return array_keys($a);
}
while ($a = each(foo()))
{
echo 'dummy';
}

produces an infinite loop. Probably since the result of array_key doesn't
support an array pointer or so, I don't know how this is internally
implemented.

Shouldn't this be considered as a bug? Shouldn't be the resulst of
array_key
walkable with each?

It's a bug alright--yours. foo() will return a fresh array each time,
so the condition is always true.

[Chung Leong]

Jim Michaels wrote:

I thought the problem was that each() will return a fresh array each time
because of foo(). each() always adds to the array foo() returns.
I also thought a better solution would be to use a foreach lop instead of
while.

each() is a real function. It isn't a language construct, unlike a
foreach() statement. foo() then each() will be called in each
iteration.