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[2009-08-16 01:20 UTC] president at basnetworks dot net
Description:
------------
The function isset() produces an incorrect result when used on an object that implements the Iterator interface, within a foreach declaration.
As illustrated below, when used outside of the foreach() declaration, isset() works as expected in the object that implements Iterator interface, returning true, causing the output 'true'.
When isset() is used within the foreach() declaration on the same object, it instead returns false, causing an empty array to be used for the foreach() loop.
There is no reason the isset() function should return anything different when used within the foreach() declaration block.
Reproduce code:
---------------
class NormalClass
{
public $a, $b, $c;
public function __construct()
{
$this->a = 'a';
$this->b = 'b';
$this->c = 'c';
}
}
class ArrayClass implements Iterator
{
private $internal_array;
public function __construct()
{
$this->internal_array = array('a', 'b', 'c');
}
public function key()
{
return key($this->nodes);
}
public function current()
{
return current($this->nodes);
}
public function next()
{
next($this->nodes);
}
public function valid()
{
return (current($this->nodes) !== false) ? true : false;
}
public function rewind()
{
reset($this->nodes);
}
}
$array = array('a', 'b', 'c');
$normal_object = new NormalClass();
$array_object = new ArrayClass();
echo "Array: " . (isset($array) ? 'true' : 'false');
echo "\nNormal Object: " . (isset($normal_object) ? 'true' : 'false');
echo "\nArray Object: " . (isset($array_object) ? 'true' : 'false');
echo "\nArray: ";
foreach ((isset($array) ? $array : array()) as $item)
{
echo $item;
}
echo "\nNormal Object: ";
foreach ((isset($normal_object) ? $normal_object : array()) as $item)
{
echo $item;
}
echo "\nArray Object: ";
foreach ((isset($array_object) ? $array_object : array()) as $item)
{
echo $item;
}
Expected result:
----------------
Array: true
Normal Object: true
Array Object: true
Array: abc
Normal Object: abc
Array Object: abc
Actual result:
--------------
Array: true
Normal Object: true
Array Object: true
Array: abc
Normal Object: abc
Array Object:
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Last updated: Fri Oct 24 22:00:02 2025 UTC |
I addition to the reproduce code, the following may help to understand the bug: foreach ($array_object as $item) { echo $item; } Will successfully print "abc", while: foreach ((isset($array_object) ? $array_object : array()) as $item) { echo $item; } will not print anything, indicating that isset() is returning false. I hope that helps.After further testing, I have found this bug is stranger than it seems: foreach ((isset($array_object) ? $array_object : array('1', '2', '3')) as $item) { echo $item; } Should either print 'abc' or '123' no matter if isset() is successful or fails. It prints neither. Now I am wondering if it is not isset(), but the ternary operator that is failing.Thank you for your bug report. I could reproduce the behavior and made a code sample to reproduce it: <?php class TestObject implements Iterator { private $first = true; function valid() { if ($this->first) { $this->first = false; return true; } return false; } function current() { } function next() { } function key() { } function rewind() { } } $array_object = new TestObject(); // Without ternary operator, the foreach is entered foreach ($array_object as $item) { echo "This works.\n"; } // With ternary operator, the foreach is not entered foreach ((true ? $array_object : $array_object) as $item) { die("Good. Expected behavior.\n"); } die("Bad. Foreach was skipped.\n"); ?>Thank you for your bug report. I could reproduce the behavior and made a code sample to reproduce it: <?php class TestObject implements Iterator { private $first = true; function valid() { if ($this->first) { $this->first = false; return true; } return false; } function current() { } function next() { } function key() { } function rewind() { } } $array_object = new TestObject(); // Without ternary operator, the foreach is entered foreach ($array_object as $item) { echo "This works.\n"; } // With ternary operator, the foreach is not entered foreach ((true ? $array_object : $array_object) as $item) { die("Good. Expected behavior.\n"); } die("Bad. Foreach was skipped.\n"); ?>