Home > PHP > Arraysprinter version

PHP Arrays

An array is an ordered set of variables where each variable is known as an element. Arrays in PHP can hold integers, floats, Booleans, strings, objects, other arrays as well as values of mixed type.

Arrays in PHP can be numbered or associative.

In a numbered array the elements are accessed by a numeric index.
In an associative array the elements are accessed by a text string. This is useful when working with databases.

Creating an Array

The array() construct is used to create an array.

A Numbered Array

The index for the first element in an array is 0 by default but it can start at any numeric value you choose.

Example of a Numbered array

<?php
    $names = array ("Tom", "Dick", "Harry");

    // Print out the second element in the array

    echo ($names[1]);
?>

To start the array index at a numeric value other than the default 0 or if you wish to leave gaps in the array it can be done as below.

Example of a Numbered array with Gaps

<?php
    /* This starts the array at element 1 and
    leaves out evenly numbered elements */

    $names = array (1=>"Tom", 3=>"Dick", 5=>"Harry");
?>

An empty array can be created and values added later in the script using the bracket syntax. If an index isn't supplied inside the bracket then PHP automatically assigns the highest current index + 1.

If an index is supplied inside the bracket then it will overwrite the current value, if it exists, with the new value.

Creating an Empty array then Updating it

<?php
    $names = array ();

    /* Later on in the script
    the values can be added */

    $names[] = "Tom";
    $names[] = "Dick";
    $names[] = "Harry";
?>

An Associative array

This is similar in form to a numbered array except that the elements are accessed by string indexes, called keys.

Example of an Associative array

<?php
    $pages = array (
    "html"=>"HTML Tutorial",
    "css"=>"CSS Tutorial",
    "php"=>"PHP Tutorial");

    /* This will print out the
    string "CSS Tutorial" */

    echo ($pages["css"]);
?>

A Heterogeneous array

PHP allows values of different types to be stored in array as shown below.

Example of a Heterogeneous array

<?php
$details = array ("Tom", 40, "Main Street", 20.4, true);
?>

Multidimensional arrays

A multidimensional array is an array that holds other array(s). This can be to be whatever depth is required.

Example of a Two Dimensional array

<?php
    $details = array (array("Tom", "Dick", "Harry"),
    array ("Main Street", "Brick Lane", "Holme Road"));

    // This will print out Brick Lane

    echo ($details[1][1]);
?>

The foreach Loop

The foreach statement is specially designed for use with arrays - both numbered and associative. The loop executes once for each element in the array and takes two forms.

The first form assigns the value in each element to a variable identified with the as keyword.
The second form assigns both the key and the value in each element to a pair of variables identified with the as keyword.

foreach Loop Using the First Form

<?php
    $list_of_names = array("Tom", "Dick", "Harry");

    foreach ($list_of_names as $name)
    {
        echo ($name.', ');
    }

    // This will print out Tom, Dick, Harry
?>

foreach Loop Using the Second Form

<?php
    $details = array("Tom" => 40, "Dick" => 36, "Harry" => 25);

    foreach ($details as $name => $age)
    {
        echo ($name.' is aged '.$age.'<br>');
    }

    /* This will print out
    Tom is aged 40
    Dick is aged 36
    Harry is aged 25
    */
?>

If the second form is used with a numbered array then the index is assigned to the variable identified with the key.

Array Pointers

Before foreach was introduced in PHP4, array pointers were used with while loops to iterate through arrays.

Since foreach is so much easier to use, the use of array pointers are not covered here.

Previous - Loops Next - Array Functions

Basics Creating a Document Head and Body Elements Formatting Text Creating Lists Embedding Images URLs Explained Linking to Documents Creating Tables Forms Form Basics Input and Textarea Select Lists Frames Framesets The Frame Element Nested Framesets Targetting Frames Inline Frames		Tips and Tricks Meta Tags Transition Effects HTML Generators Create a Document Create a List Create a Table

Basics Implementing CSS CSS Syntax Pseudo Classes/Elements CSS Classes CSS Properties Font Properties Color and Background Text Properties Border Properties Margins and Padding Size and Position		Tips and Tricks Menu Buttons Special Effects

Basics Running a Script Variables Expressions and Operators Objects.Properties.Methods The Date Object Strings Regular Expressions Defining RegExp Patterns Branches and Conditions Loops Arrays Array Basics Array Methods Sorting Arrays User-Defined Functions Cookies Windows Frames		Tips and Tricks Image Replacement Using Includes Form Validation Debugging

Basics Creating a Script Running a Script Variables Expressions and Operators Strings Strings Basics Strings and Substrings Replacing Substrings Regular Expressions Branches and Conditions Loops Arrays Array Basics Array Functions Sorting Arrays User-Defined Functions Include and Require Uploading Files File Functions Session Variables		Tips and Tricks Page Templates Form Reply Scripts Form Validation JavaScript to PHP