In this article, Eric will denomonstrate the use of arrays in PHP. This article is mainly for beginner PHP programmers to give them a push in the right direction.
What is an Array?
Arrays can most easilly be described as an ordered list. An array is a list of scalar data (If you don't know what a scalar variable is, you should take a look at my first tutorial. Scalar data in arrays are called 'elements'.) that is 'indexed' (so to speek) with numeric or named keys. A 'key' is either a name or a number given to an element in an array as a reference (if a key is numeric, it is called a 'subscript').
An Example of an Array
<?php
$six = 6;
$arrayname = array("this is an element",5,$six);
echo $arrayname[0]; //prints: this is an element
echo $arrayname[1]; //prints: 5
echo $arrayname[2]; //prints: 6
?>
As you can see, elements in an array can be any type of scalar data (string, integer, double) and can also be other variables. In this example, the 'keys' are numeric (assigned automatically for you), so when echo'ing the elements, you use the array name followed by the subscript ($arrayname[subscript]). Notice that the subscript of the first element is zero? This will always be the case with numeric keys.
Associative Arrays
Associative arrays are arrays that use named keys that you assign to them. Lets look at a few examples...
<?php
$arrayone = array("key1" => "this is the first element.", "key2" => "this is the second element");
$arraytwo = array(
"key3" => "this is the first element of the second array",
"key4" => "this is the second element of the second array",
);
echo $arrayone['key1']; //prints "this is the first element."
echo $arraytwo['key3']; //prints "this is the first element of the second array"
echo $arrayone['key2']; //prints "this is the second element"
echo $arraytwo['key4']; //prints "this is the second element of the second array"
?>
Now we're getting to where you know how to define an array (and an associative array), but you probably don't see how there useful yet. Well think of this, say you have a bakery that sells pies. You have 3 different flavors, and each flavor has a different price. lets make this example in php...
<?php
$bakery = array(
"cherry" => "5.00",
"apple" => "4.00",
"other" => "2.00",
);
echo "cherry pie costs $bakery['cherry'], apple pie costs $bakery['apple'], and that other pie costs $bakery['other'].";
?>
Ok, you've got an example of how to use arrays (a very basic example, grant me that). But what if you want to give more information on each pie? You now have the cost, but what if you wanted to add the number of pieces you get for that price, and if the pie was sugarless or not? One way is using mutlidimensional arrays.
Multidimensional Arrays
Think of multidimensional arrays as simply a list of arrays. This might seem confusing at first, but im sure with a few examples (and a few pies) you will get the big picture. Pick up your fork, its time to eat:
<?php
$bakery = array(
"cherry" => array("5.00","2 pieces","sugar"),
"apple" => array("4.00","3 pieces","sugar"),
"other" => array("2.00","1 piece","sugar-free"),
);
echo "cherry pie costs ".$bakery['cherry'][0].", and you get ".$bakery['cherry'][1].".";
//prints "cherry pie costs 5.00, and you get 2 pieces."
echo "apple pie costs ".$bakery['apple'][0].", and you get ".$bakery['apple'][1].".";
//prints "apple pie costs 4.00, and you get 3 pieces."
echo "the other pie costs ".$bakery['other'][0].", but its ".$bakery['other'][2].".";
//prints "the other pie costs 2.00, but its sugar-free.
?>
Hopefully now you will be prepared to use arrays when you begin querying mysql databases, and performing other forms of intermediate to advanced data manipulation. If you've noticed, this 'tutorial' wasn't really a tutorial. I'm only trying to give you the basic idea of how to define and use these arrays, not give you all the information a person could possibly fathom. Hey, that might explain the whole "Introduction" word in the title.
Related Functions
array_change_key_case -- Returns an array with all string keys lowercased or uppercased
array_chunk -- Split an array into chunks
array_count_values -- Counts all the values of an array
array_diff_assoc -- Computes the difference of arrays with additional index check
array_diff -- Computes the difference of arrays
array_fill -- Fill an array with values
array_filter -- Filters elements of an array using a callback function
array_flip -- Flip all the values of an array
array_intersect_assoc -- Computes the intersection of arrays with additional index check
array_intersect -- Computes the intersection of arrays
array_key_exists -- Checks if the given key or index exists in the array
array_keys -- Return all the keys of an array
array_map -- Applies the callback to the elements of the given arrays
array_merge_recursive -- Merge two or more arrays recursively
array_merge -- Merge two or more arrays
array_multisort -- Sort multiple or multi-dimensional arrays
array_pad -- Pad array to the specified length with a value
array_pop -- Pop the element off the end of array
array_push -- Push one or more elements onto the end of array
array_rand -- Pick one or more random entries out of an array
array_reduce -- Iteratively reduce the array to a single value using a callback function
array_reverse -- Return an array with elements in reverse order
array_search -- Searches the array for a given value and returns the corresponding key if successful
array_shift -- Shift an element off the beginning of array
array_slice -- Extract a slice of the array
array_splice -- Remove a portion of the array and replace it with something else
array_sum -- Calculate the sum of values in an array.
array_unique -- Removes duplicate values from an array
array_unshift -- Prepend one or more elements to the beginning of array
array_values -- Return all the values of an array
array_walk -- Apply a user function to every member of an array
array -- Create an array
arsort -- Sort an array in reverse order and maintain index association
asort -- Sort an array and maintain index association
compact -- Create array containing variables and their values
count -- Count elements in a variable
current -- Return the current element in an array
each -- Return the current key and value pair from an array and advance the array cursor
end -- Set the internal pointer of an array to its last element
extract -- Import variables into the current symbol table from an array
in_array -- Return TRUE if a value exists in an array
key -- Fetch a key from an associative array
krsort -- Sort an array by key in reverse order
ksort -- Sort an array by key
list -- Assign variables as if they were an array
natcasesort -- Sort an array using a case insensitive "natural order" algorithm
natsort -- Sort an array using a "natural order" algorithm
next -- Advance the internal array pointer of an array
pos -- Get the current element from an array
prev -- Rewind the internal array pointer
range -- Create an array containing a range of elements
reset -- Set the internal pointer of an array to its first element
rsort -- Sort an array in reverse order
shuffle -- Shuffle an array
sizeof -- Get the number of elements in variable
sort -- Sort an array
uasort -- Sort an array with a user-defined comparison function and maintain index association
uksort -- Sort an array by keys using a user-defined comparison function
usort -- Sort an array by values using a user-defined comparison function
| DISCLAIMER: The content provided in this article is not warranted or guaranteed by Developer Shed, Inc. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. As such it is incumbent upon the reader to employ real-world tactics for security and implementation of best practices. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. If this is a hardware review, it is not recommended to open and/or modify your hardware. |
More PHP Articles
More By Eric 'phpfreak' Rosebrock
 developerWorks - FREE Tools!
|
Build secure Web services with transport-level security using IBM Rational Application Developer V7 and IBM WebSphere Application Server V6.1. Follow this three-part series for step-by-step instructions about how to develop Web services and clients, configure HTTP basic authentication, and configure HTTP over SSL (HTTPS). This first part of the series walks you through building a Web service for a simple calculator application. You generate and test two different types of Web services clients: a Java Platform, Enterprise Edition (Java EE) client and a stand-alone Java client. You also handle user-defined exceptions in Web services.
FREE! Go There Now!
|
|
|
|
Visit IBM developerWorks to download a free trial version of Lotus Quickr 8.0, which enables collaboration by transforming the way everyday business content such as documents, rich media, photos, and video can be shared. Lotus Quickr makes it faster and easier to share content of all types (not just documents) within virtual teams. It is designed to make it easier to collaborate across organizational boundaries, while continuing to work within the context of familiar desktop applications.
FREE! Go There Now!
|
|
|
|
Visit IBM developerWorks to download IBM DB2 Express-C 9.5, a no-charge version of DB2 Express 9 database server. DB2 Express-C offers the same core data server base features as other DB2 Express editions and provides a solid base to build and deploy applications developed using C/C++, Java, .NET, PHP, and other programming languages.
FREE! Go There Now!
|
|
|
|
Download a free trial version of IBM Rational Developer for System z, software that can help you deliver core development capabilities; the power of Java Platform, Enterprise Edition (Java EE); and rapid application development support to diverse enterprise application development teams. With comprehensive development tools to help create, deploy and maintain traditional enterprise and composite applications, Rational Developer for System z enables developers with different technical backgrounds to easily participate in important technology projects.
FREE! Go There Now!
|
|
|
|
In this tutorial, you can learn how to install and configure the IBM Rational Asset Manager Eclipse client, explore the different views in the Asset Management perspective, learn various search techniques, work with existing assets, and submit a new asset.
FREE! Go There Now!
|
|
|
|
Discover how Rational tools and best practices for testing can make your job easier. The new Rational Testing eKits provide you with valuable resources – including demos, webcasts, tutorials, and articles – that help you address your specific testing needs across the software lifecycle. Five new eKits are available covering the topics of Requirements and Test Management, Functional Testing, Performance Testing, Code Quality and Embedded Systems, and SOA and Web Services Testing.
FREE! Go There Now!
|
|
|
|
Because access to government information continues to be an area of concern for many U.S. citizens with disabilities, the U.S. government enacted Section 508 of the Rehabilitation Act in 2001 to ensure that government agencies create accessible Web content, enabling all citizens to access the information they need. A fully accessible Web site makes Web content accessible to all individuals, including those with disabilities, who may be accessing Web content via a variety of user agents. Common user agents include standard Web browsers, text-only browsers, assistive devices and mobile devices such as cell phones or personal digital assistants (PDAs).
FREE! Go There Now!
|
|
|
|
Get a free trial download of IBM Lotus Forms V3.0 (formerly Workplace Forms), which provides a zero-footprint eForms solution to help you automate and move forms-based business processes off the desktop and onto the Web. With Lotus Forms, you can extend applications beyond the firewall by creating a single electronic form document ready for use in both thick and Web 2.0 thin client format.
FREE! Go There Now!
|
|
|
|
Visit IBM developerWorks to try the IBM SOA Sandbox for process. The SOA Sandbox for process focuses on providing a trial environment with the necessary tooling and components required to gain a better understanding of business processes and how to best improve existing business processes to derive value quickly.
FREE! Go There Now!
|
|
|
|
As businesses grow increasingly dependent upon Web applications, these complex entities grow more difficult to secure. Most companies equip their Web sites with firewalls, Secure Sockets Layer (SSL), and network and host security, but the majority of attacks are on applications themselves – and these technologies cannot prevent them. This paper explains what you can do to help protect your organization, and it discusses an approach for improving your organization’s Web application security.
FREE! Go There Now!
|
|
|
|
All FREE IBM® developerWorks Tools!
|
/ 4 
