Question

Since PHP doesn’t provide real arrays, I want to create an array class myself. However, preferably I don’t want to create some sort of wrapper class for the PHP array, but I really want to create a real array, like in C/C++. However, if I don’t want to use the build in PHP array, I need to have some way to allocate memory manually, and to find the size of an object/class. So I need a PHP version of the c functions sizeof and malloc. Unfortunately, I couldn’t find those in PHP. Are there functions which do the same thing, or do you know of any other way to do this?

Edit: I think my question isn’t clear enough:
In PHP an array is really an order map. In some situations this can make things a little more complicated: for example, if you have an array with indices 0,1,2 and 3, you can’t relay on that you will get those items in that order in a foreach loop: it depends on the order in which you defined the items in the array. Since those little things annoy me, I want to create a ‘real’ array class, based on arrays like they are in c/c++. That means that the arrays should have a fixed size, and that I need to allocate memory manually when an array is initialized. For example, when an array of 10 integers is created, the array class should allocate a memory block of the size 10*sizeof(integer). Of course I could use the build in PHP ‘array’ to store these 10 integers, but than I’ve just created a wrapper class for the build in array type. So preferably I want to be able to allocate that memory myself so I can manage it in a better way that the build in array type does. However, I couldn’t find a function which gives me the size of a class/object, and I could find a function which could allocate memory manually, like malloc does in c.
So my question is: are there any functions for this? And if they aren’t, do you have any other efficient ways to achieve my goal?

Answer 1

PHP already has an Array Class with SplFixedArray which behaves like you want:

$array = new SplFixedArray(3);
$array[1] = 'foo';
$array[0] = 'bar';
$array[2] = 'baz';
foreach ($array as $k => $v) {
    echo "$k => $v\n";
}
$array[] = 'fails';

gives

0 => bar
1 => foo
2 => baz

and finally

Fatal error: Uncaught exception ‘RuntimeException’ with message ‘Index invalid or out of range’

There is a couple of additional data structures in SPL. For an overview, see

• http://matthewturland.com/2010/05/20/new-spl-features-in-php-5-3/

If you want to know how SplFixedArray is implemented in PHP, have a look at

• http://lxr.php.net/opengrok/xref/PHP_TRUNK/ext/spl/spl_fixedarray.c

If you want anything different, you will probably have to implement that at the C level of the language, e.g. you’d have to write your own extension.