PHP Indexed Arrays

An indexed array is a simple array in which data elements are stored against numeric indexes. All the array elements are represented by an index which is a numeric value starting from 0 for the first array element.

Creating an Indexed Array

There are two different ways of creating an indexed array in PHP, they are,

Syntax for the 1st way to create indexed array:

<?php
/* 
    1st - direct array initialization
*/
$lamborghinis = array("Urus", "Huracan", "Aventador");

?>

and the syntax for the 2nd way to create indexed array is:

<?php
/* 
    2nd - distributed array initialization
*/
$suzuki[0] = "Swift";
$suzuki[1] = "Baleno";
$suzuki[2] = "Ertiga";
$suzuki[3] = "Brezza";
$suzuki[4] = "Vitara";

?>

No matter how we initialize the array, we can access the array as follows,

<?php
/* 
    Accessing array
*/
echo "Accessing the 2nd array...";
echo $suzuki[0], "\n";
echo $suzuki[3], "\n";
echo $suzuki[2], "\n";

echo "Accessing the 1st array...";
echo $lamborghinis[1], "\n";
echo $lamborghinis[0], "\n";
echo $lamborghinis[2], "\n";

?>

Accessing the 2nd array... Swift Brezza Ertiga Accessing the 1st array... Huracan Urus Aventador

Hence, to access an indexed array, we have to use the array name along with the index of the element in square brackets.

Traversing PHP Indexed Array

Traversing an array means to iterate it starting from the first index till the last element of the array.

We can traverse an indexed array either using a for loop or foreach. To know the syntax and basic usage of for and foreach loop, you can refer to the PHP for and foreach loop tutorial.

Using for loop

While using the for loop to traverse an indexed array we must know the size/length of the array, which can be found using the count() function.

Following is the syntax for traversing an array using the for loop.

<?php

$lamborghinis = array("Urus", "Huracan", "Aventador");
// find size of the array
$size = count($lamborghinis);

// using the for loop
for($i = 0; $i < $size; $i++)
{
    echo $lamborghinis[$i], "\n";
}

?>

Using the foreach loop

using foreach to traverse an indexed array is a better approach if you have to traverse the whole array, as we do not have to bother about calculating the size of the array to loop around the array.

Below we have used the foreach to traverse the $lamborghinis array.

<?php

$lamborghinis = array("Urus", "Huracan", "Aventador");

// using the foreach loop
foreach($lamborghinis as $lambo)
{
    echo $lambo. "\n";
}

?>

Advantages of Indexed Array

Here are a few advantages of using indexed array in our program/script:

1. Numeric index values make it easier to use and having numeric indexes are common to almost all the programming languages, hence it also makes the code more readable for others who go through your code.