When we talk about storing values in PHP, we talk about the word array. To store multiple values, there are two ways of carrying out the task. One way is to assign each value to a single variable, and the other, much more efficient way, is to assign multiple values to a single variable. That is what we call an array. 

An array is a way to store multiple values in a single variable. Arrays, thus, form an important part of the programming communities go-to tools. Arrays can store both numeric as well as string values and can have multiple dimensions.

Thus, an array with more than one dimension is called a multidimensional array in PHP, which we’ll talk in great detail through hands-on examples later in the article.

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To get a better sense of what an array is and its dimensions, let’s go through an example. 

Suppose you go to a supermarket and buy a pack of biscuits. When you open the pack, the biscuits are lined up one after the other. This means they are arranged in a linear fashion, and hence, this is an example of a one-dimensional array. 

Next, you think of buying a pack of assorted dry fruits. Now when you open the pack, there are slots both along the width and length of the box in which different dry fruits are kept. That forms an example of a two-dimensional array where the box represents the array, and the dry fruits in the slots make up the elements.

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When we talk of arrays, we talk about them in two terms – what type an array is and what are its characteristics or attributes. The type of array is defined by its dimensions. By that virtue, there are two types: one-dimensional or single-dimensional and multidimensional array in PHP.

As already explained in the examples above, you must have gotten an idea of an array’s dimensions. So, to access an element is a one-dimensional array, you need just one index.

But to access an element in a multidimensional array in PHP, you require two indices for two-dimensional, three for three-dimensional array, and so on. Thus, a multidimensional array is defined as an array of arrays or sub-arrays, as the case may be.

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The characteristics of an array can be classified as either numeric or associative.

• Numeric array is an array which uses numbers to access its elements stored in the array.
• Associative array uses strings or names to access the elements stored. For example, an employee’s name to access data from the company register or server.

Following is the syntax for defining a one-dimensional numeric array:

<?php

$variable name = array(‘index no.’ => ‘element’,…);

?>

Where,

‘$variable name’ is the name of the array

‘index no.’ refers to the index of the stored element

‘element’ refers to the stored value

Note that the default index number always starts with ‘0’.

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Let’s look at an example

<?php

//Program for creating one dimensional numeric array

$Car Brands = array ( 0 => ‘BMW’,

                                  1 => ‘Land Rover’,

        2 => ‘Ferrari’,

       3 => ‘Ford’,

                                   4 => ‘Toyota’ );

Print_r($Car Brands);

?>

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Output:

Array

(

  [0] => BMW

  [1] => Land Rover

  [2] => Ferrari

  [3] => Ford

  [4] => Toyota

)

As we can see from the output, the car brands are assigned to and accessed by numeric keys 0, 1, 2, …, etc.

Let’s take a look at a one-dimensional associative array; following is the syntax for the same:

<?php

$variable name = array( ‘string/key’ => ‘element’,…);

?>

Where,

‘$variable name’ is the name of the array

‘string/key’ refers to the id of the stored element

‘element’ refers to the stored value

Here’s an example of an associative one-dimensional array. Suppose we want to store the names of a few countries and the respective continent they lie in.

<?php

$Countries = array(

“Italy” => “Europe”,

                                  “India” => “Asia”,

                                  “Brazil” => “South America”

                                 “Mexico” => “North America”,

                          );

echo “Mexico is in” $Countries [“Mexico”];

?>

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Output:

Mexico is in North America

Now it’s time to understand how a multidimensional array in PHP works. Here’s the syntax.

<?php

$variable name =array(

                           Array1( ‘string/key’ => ‘element’,…),

                           Array2( ‘string/key’ => ‘element’,…),…

                         );

?>

We can arrange arrays in terms of groups or patterns. For example, we can arrange car models based on their body types. Here’s an example code.

<?php

$Car body styles = array(

                        “SUV” => array( “Scorpio”, “Harrier”, “Creta”, “Seltos”, “Fortuner”),

                        “Hatchback” => array( “Swift”, “Jazz”, “Tiago”, “i20”)’

                      “MPV” => array( “Ertiga”, “Innova”, “Triber”)

                      );

Echo $Car body styles[“SUV”][3];

?>

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Output:

Creta

Let’s quickly create a three-dimensional array by adding sales data to the previous example.

<?php

$Car body styles = array(

                                 “SUV” => array(

                                                          “Scorpio” => array(“Jan 20” =>“4521”, “Feb 20” => “3589”),

                                                          “Harrier” => array(“Jan 20” =>“1987”, “Feb 20”=> “2356”),

                                                          “Creta” => array(“Jan 20” => “10459”, “Feb 20” => “9887”),

                                                         “Seltos” => array(“Jan 20” => “12549”, “Feb 20” => “13589”),

                                                        “Fortuner” => array(“Jan 20” => “1897”, “Feb 20” => “1692”),

                                                       ),

     “Hatchback” => array(

                                                          “Swift” => array(“Jan 20” =>“19875”, “Feb 20” => “18521”),

                                                          “Jazz” => array(“Jan 20” =>“2451”, “Feb 20”=> “2390”),

                                                          “Tiago” => array(“Jan 20” => “6587”, “Feb 20” => “8850”),

                                                       ),

                             “MPV” => array(

                                                          “Ertiga” => array(“Jan 20” =>“5680”, “Feb 20” => “4920”),

                                                          “Innova” => array(“Jan 20” =>“2540”, “Feb 20”=> “2135”)

                          );

Echo “The sales of Creta for the month of Jan’ 20 are” $Car body styles[“SUV”][“Creta”][“Jan20”];

?>

Output:

The car sales of Creta for the month of Jan’ 20 are 10459

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Conclusion

So, we can conclude that arrays are an efficient and flexible form of data storage and access. Arrays can be stretched or compressed as per the need, which allows for easy modification. Associative multidimensional arrays help us group together related data. Apart from that, arrays help in achieving a clutter-free and cleaner code. Plus, you can perform a number of operations on an array, such as sorting, counting, etc.

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