Questions tagged [php-internals]
How the PHP programming language works underneath, and questions about the underlying C code.
php-internals
46
questions
2282
votes
7
answers
459k
views
How does PHP 'foreach' actually work?
Let me prefix this by saying that I know what foreach is, does and how to use it. This question concerns how it works under the bonnet, and I don't want any answers along the lines of "this is how you ...
- 88.4k
52
votes
2
answers
3k
views
Parentheses altering semantics of function call result
It was noted in another question that wrapping the result of a PHP function call in parentheses can somehow convert the result into a fully-fledged expression, such that the following works:
<?php
...
19
votes
7
answers
3k
views
print_r() adds properties to DateTime objects [duplicate]
Consider the following code sample:
$m_oDate = new DateTime('2013-06-12 15:54:25');
print_r($m_oDate);
echo $m_oDate->date;
Since PHP 5.3, this produces (something like) the following output:
...
- 217
43
votes
6
answers
6k
views
Why don't PHP attributes allow functions?
I'm pretty new to PHP, but I've been programming in similar languages for years. I was flummoxed by the following:
class Foo {
public $path = array(
realpath(".")
);
}
It produced a ...
- 161k
27
votes
5
answers
7k
views
Detecting whether a PHP variable is a reference / referenced
Is there a way in PHP to determine whether a given variable is a reference to another variable and / or referenced by another variable? I appreciate that it might not be possible to separate ...
- 17.3k
133
votes
41
answers
187k
views
What does "zend_mm_heap corrupted" mean
All of the sudden I've been having problems with my application that I've never had before. I decided to check the Apache's error log, and I found an error message saying "zend_mm_heap corrupted". ...
- 1,694
13
votes
2
answers
4k
views
What is #<some-number> next to object(someClass) in var_dump of an object? I have an inference. Am I right?
This is the code & its output I used to draw the inference below:
class a {
public $var1;
public $var2;
}
$obj0 = new a;
var_dump($obj0);
class b {
public $var1;
public $...
- 12.7k
26
votes
5
answers
10k
views
How are associative arrays implemented in PHP?
Can someone explain how PHP implements associative arrays? What underlying data structure does PHP use? Does PHP hash the key and store it in some kind of hash map? I am curious because I was ...
Y Pgjn
15
votes
3
answers
15k
views
Getting Started with PHP Extension-Development [closed]
Please suggest help articles or tutorials about PHP "low" level С-modules programming interface.
- 1,893
31
votes
4
answers
7k
views
Where can I learn about PHP internals? [closed]
What are good resources to start learning the internals of PHP and the Zend Engine?
- 22.8k
2
votes
1
answer
254
views
Why does a PHP array get modified when it's element is reference-assigned?
When ref-assigning an array's element, the contents of the array are modified:
$arr = array(100, 200);
var_dump($arr);
/* shows:
array(2) {
[0]=>
int(100) // ← ← ← int(100)
[1]=>
int(...
- 88.6k
22
votes
4
answers
4k
views
How does PHP memory actually work
I've always heard and searched for new php 'good writing practice', for example: It's better (for performance) to check if array key exists than search in array, but also it seems better for memory ...
- 7,639
21
votes
3
answers
11k
views
Reading Zend Engine API code: What does ## (double hash) mean?
Out of curiousity, I'm reading the Zend Engine API code and encountered quite a number of ## in their #define's. For example, at /usr/lib/php5/Zend/zend_API.h:
#define ZEND_FN(name) zif_##name
#...
- 1,112
12
votes
1
answer
4k
views
How does PHP assign and free memory for variables?
I was wondering when does PHP free the memory which is used for a variables
for example
function foo(){
$foo = 'data';
return $foo; // <- is the memory space for `$foo` emptied at this point?...
- 67.5k
6
votes
8
answers
3k
views
Compare PHP Arrays Using Memory References
Is it possible to see if two array variables point to the same memory location? (they are the same array)
- 28.1k