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4.1.3 Multidimensional Arrays

In the previous pages, we have described arrays that are a single list of key/value pairs.
However, sometimes you want to store values with more than one key. For this, we have multidimensional arrays.

PHP - Multidimensional Arrays

A multidimensional array is an array containing one or more arrays.
PHP supports multidimensional arrays that are two, three, four, five, or more levels deep. However, arrays more than three levels deep are hard to manage for most people.

The dimension of an array indicates the number of indices you need to select an element.

For a two-dimensional array you need two indices to select an element
For a three-dimensional array you need three indices to select an element

PHP - Two-dimensional Arrays

A two-dimensional array is an array of arrays (a three-dimensional array is an array of arrays of arrays).
First, take a look at the following table:

Name	Stock	Sold
Volvo	22	18
BMW	15	13
Saab	5	2
Land Rover	17	15

We can store the data from the table above in a two-dimensional array, like this:

$cars = array (
  array("Volvo",22,18),
  array("BMW",15,13),
  array("Saab",5,2),
  array("Land Rover",17,15)
);

Now the two-dimensional $cars array contains four arrays, and it has two indices: row and column.
To get access to the elements of the $cars array we must point to the two indices (row and column):

Example 1: PHP Arrays - Two-dimensional Arrays

<?php
echo $cars[0][0].": In stock: ".$cars[0][1].", sold: ".$cars[0][2].".<br>";
echo $cars[1][0].": In stock: ".$cars[1][1].", sold: ".$cars[1][2].".<br>";
echo $cars[2][0].": In stock: ".$cars[2][1].", sold: ".$cars[2][2].".<br>";
echo $cars[3][0].": In stock: ".$cars[3][1].", sold: ".$cars[3][2].".<br>";
?>

We can also put a for loop inside another for loop to get the elements of the $cars array (we still have to point to the two indices):

Example 2: PHP Arrays - Two-dimensional Arrays with for loop

<?php
for ($row = 0; $row < 4; $row++) {
  echo "<p><b>Row number $row</b></p>";
  echo "<ul>";
  for ($col = 0; $col < 3; $col++) {
    echo "<li>".$cars[$row][$col]."</li>";
  }
  echo "</ul>";
}
?>

Complete PHP Array Reference

For a complete reference of all array functions, go to the W3Schools.com complete PHP Array Reference.
The reference contains a brief description, and examples of use, for each function!

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Example files created in this module:
PHP Arrays Array Items PHP Arrays - Get The Length of an Array with The count() Function PHP Arrays - Change Value Indexed Arrays - Loop Through an Indexed Array PHP Arrays: Index Number part 1 PHP Arrays: Index Number part 2 PHP Arrays - Associative Arrays part 1 PHP Arrays - Associative Arrays part 2 PHP Arrays - Access Associative Arrays PHP Associative Arrays: Change Key's Value Associative Arrays - Loop Through an Associative Array part 1 Associative Arrays - Loop Through an Associative Array part 2 PHP Arrays - Two-dimensional Arrays PHP Arrays - Two-dimensional Arrays with for loop PHP Arrays - Sorting Arrays part 1 PHP Arrays - Sorting Arrays part 2 PHP Arrays - Sort Array in Descending Order rsort() part 1 PHP Arrays - Sort Array in Descending Order rsort() part 2 PHP Arrays - Sort Array (Ascending Order), According to Value asort() PHP Arrays - Sort Array (Ascending Order), According to Key ksort() PHP Arrays - Sort Array (Descending Order), According to Value arsort() PHP Arrays - Sort Array (Descending Order), According to Key krsort() PHP $GLOBALS PHP $_SERVER PHP $_REQUEST - Form Submission PHP $_POST - Form Submission Test Get PHP RegEx - Using preg_match() PHP RegEx - Using preg_match_all() PHP RegEx - Using preg_replace() PHP RegEx - Grouping