DragonBe's PHP blog

Associative array or hash maps are listings of key and value pairs with a posibility to nest additional keys and values. An associative array is a very powerful construct within PHP.

In our previous article we discussed simple arrays, which in their turn are indexed associative arrays under the hood. Take the following example:

$array = [
'apple',
'banana',
'chocolate',
]; 

Is in fact an indexed associative array under the hood:

$array = [
0 => 'apple',
1 => 'banana',
2 => 'chocolate',
]; 

But associative arrays can be so much more than just an indexed array, and you will find many database operations returning arrays where the fields of a table are the keys in the array while their values are also the values within the array.

$productRowData = [
'product_id' => 1234,
'brand_id' => 321,
'product_name' => 'Our awesome product',
'prodcut_description' => 'This is our most awesome product.&#…

Like all things in life, we need to start with simple things. So, in order to understand what arrays are in PHP, we need to take a look at the PHP manual to read what it is all about:
An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more. The thing with PHP is that an array is probably one of the most used data structures in web applications build with PHP and used for a wide variety of purposes.

Let's look at a first usage of an array: storing multiple values in a list.

<?php
$array = [
'foo',
'bar',
'baz',
];

This is a PHP array with 3 elements. Now we can add an element at the end of this array.

// Adding an element at the of the array 
array_push($array, 'foobar');

Or even more efficient:

$array[] = 'barbaz';

Now ou…

In 2015 we celebrated the twentieth birthday of PHP and we even had the release of php-7.0.0. Life is all good!

I wish it was all this peachy. In my work as a consultant or when I'm working on OSS projects I cannot help noticing that some of the basics of PHP are missing, especially when dealing with arrays.

To give you an example: developers and site owners often complain about their web application being slow. When I get called in to improve performance, I stumble on a huge number of foreach-loops when processing data retrieved from a database. The first iteration happens right at data retrieval where the result set is iterated over to produce a new array of data models.

/** * Fetches all entries, optionally matching provided conditions, * optionally ordered by provided order, optionally limited by * provided number of entries with an optional provided offset. * * @param array $where * @param array $order * @param int $limit * @param int $offset * @return array */ publ…