php-internals

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 wondering what the performance of associative arrays where when inserting and searching for keys. It's a hash table. The type declaration and hashing function are here: http://svn.php.net/viewvc/php/php-src/trunk/Zend/zend_hash.h?view=markup There is a light weight array and a linked list within the spl (standard php lib) Well, for what it is worth, all PHP arrays are Associative arrays. The highest voted

Please suggest help articles or tutorials about PHP "low" level С-modules programming interface. Pascal MARTIN Searching through my bookmarks, only links I found are those : Extension Writing Part I: Introduction to PHP and Zend Extension Writing Part II: Parameters, Arrays, and ZVALs Extension Writing Part II: Parameters, Arrays, and ZVALs [continued] Extension Writing Part III: Resources Wrapping C++ Classes in a PHP Extension If you are really interested by the subject, and ready to spend some money on it, you could buy the book Extending and Embedding PHP ( some pages are available as

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 $var2; public $var3; } $obj1 = new b; var_dump($obj1); $obj2 = new stdClass; var_dump($obj2); $obj3 = new stdClass; var_dump($obj3); $obj4 = new stdClass; var_dump($obj4); $obj5 = new stdClass; var_dump($obj5); var_dump(new stdClass); $obj6 = new stdClass; var_dump($obj6); The output: object(a)#1 (2) { ["var1"]=> NULL ["var2"]=> NULL } object(b)#2 (3) { ["var1"]=> NULL ["var2"]=> NULL ["var3"]=> NULL } object(stdClass)#3 (0) {

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 syntax error: Parse error: syntax error, unexpected '(', expecting ')' in test.php on line 5 which is the realpath call. But this works fine: $path = array( realpath(".") ); After banging my head against this for a while, I was told you can't call functions in an attribute default; you have to do it in __construct . My question is: why?! Is this a "feature" or sloppy implementation? What's the rationale? The

This question already has an answer here: Why can't I access DateTime->date in PHP's DateTime class? Is it a bug? 5 answers 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: DateTime Object ( [date] => 2013-06-12 15:54:25 [timezone_type] => 3 [timezone] => Europe/Amsterdam ) 2013-06-12 15:54:25 However the following code: $m_oDate = new DateTime('2013-06-12 15:54:25'); echo $m_oDate->date; ...simply emits an error: Notice: Undefined property: DateTime::

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 error_reporting(E_ALL | E_STRICT); function get_array() { return array(); } function foo() { // return reset(get_array()); // ^ error: "Only variables should be passed by reference" return reset((get_array())); // ^ OK } foo(); I'm trying to find anything in the documentation to explicitly and unambiguously explain what is happening here. Unlike in C++, I don't know enough about the PHP grammar and