Intro to Arrays in PHP

// August 26th, 2005 // Technology Bits

PHP has the ability to use associative arrays. These are by far the most useful and versatile data structure in PHP (and debatably any language). Instead of using the more common indexed array, where integers are used to identify the elements of the array, you can use strings.

If you are writing PHP, you have to know associative arrays and feel good about them.

Here's an example showing some common uses:

PLAIN TEXT

PHP:

$arr = array('foo' => 'bar', 12 => true);
echo $arr['foo']; // bar
echo $arr[12]; // 1
$arr['monkey'] = true;
echo $arr['monkey']; // true</code>

Associative arrays are also the most readable and convenient way to deal with database results. Suddenly you have an array that is indexed by field name from the table. How could anything be cooler than that?

For debugging arrays, there is nothing more useful than print_r():

PLAIN TEXT

PHP:

$array = array(1, 2, 3, 4, 5);
print_r($array);

Output:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
    [4] => 5
)

If you want to add an element to the end of an array you can use the [] notation (sort of like a stack push):

PLAIN TEXT

PHP:

$arr = array('Monkey', 'Alligator');
$arr[] = 'Rabbit';
print_r($arr);

Output:

Array
(
    [0] => Monkey
    [1] => Alligator
    [2] => Rabbit
)

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11 Responses to “Intro to Arrays in PHP”

NoSheep! » ADOdb - PHP Database Abstraction says:

August 27, 2005 at 11:45 am

[...] Comparing the two examples it’s clear how similar connecting to either database becomes. Also notice we’re setting the fetch mode to associative so we get back friendly associative arrays. The following is an example of how to query and get back results: [...]
NoSheep! » CS3020 - PHP: Introduction says:

September 30, 2005 at 2:13 pm

[...] arrays [...]
NoSheep! » Firefox Form Difficulty says:

November 4, 2005 at 2:52 pm

[...] So, I took the form and started some known array debugging techniques, mainly a simple print_r($_POST) which showed all the array elements with proper values in IE, but with Firefox they all had the default form values. Strange. [...]
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No Sheep