Arrays in PHP

Use Arrays to Get a Raise

By David Haskins

Use Arrays to Get a Raise*

By David Haskins

*No raise guaranteed or implied. Raises are subject to availability. Contact your supervisor for details. Offer not valid where prohibited.

Data types

A data type is a set of data (information) with certain characteristics.

PHP has:• Booleans • Integers• Floating point numbers• Strings• Arrays• Objects

Data types


PHP has: Primitive data types• Booleans (true,false)• Integers • Floating point numbers• Strings• Arrays • Objects

Data types


PHP has: Primitive data types• Booleans (true,false)• Integers (…-2,-1,0,1,2,3,4,5…)• Floating point numbers • Strings• Arrays • Objects

Data types


PHP has: Primitive data types• Booleans (true,false)• Integers (…-2,-1,0,1,2,3,4,5…)• Floating point numbers (3.14159,2.71828…)• Strings • Arrays• Objects

Data types


PHP has: Primitive data types & Composite data types

• Booleans (true,false)• Integers (…-2,-1,0,1,2,3,4,5…)• Floating point numbers (3.14159,2.71828…)• Strings ('Memphis', 'Meetup Group'…)• Arrays • Objects

Data types



• Booleans (true,false)• Integers (…-2,-1,0,1,2,3,4,5…)• Floating point numbers (3.14159,2.71828…)• Strings ('Memphis', 'Meetup Group'…)• Arrays ($_SERVER, $user = new array()…)• Objects

Data types



• Booleans (true,false)• Integers (…-2,-1,0,1,2,3,4,5…)• Floating point numbers (3.14159,2.71828…)• Strings ('Memphis', 'Meetup Group'…)• Arrays ($_SERVER, $user = new array()…)• Objects (user, animal, bird…)

What is an array?

A data structure in which similar elements of data are arranged in a table.

- http://www.merriam-webster.com/dictionary/array

An ordered collections of items, called elements. - Zend PHP 5 Certification Study Guide

An ordered map. A map is a type that associates values to keys.

- http://us2.php.net/manual/en/languages.types.array.php

How do you create an array?

//create an empty array

$cool_guys = new array();


//create a populated array

$cool_guys = array(

'Alan Turing',

'Donald Knuth',

'Rasmus Lerdorf',

'John Von Neumann');


//echo Donald Knuth

$cool_guys = array(

'Alan Turing',

'Donald Knuth',

'Rasmus Lerdorf',


echo $cool_guys[1];


//create a populated associative array

$cool_guys = array(

'computers' => 'Alan Turing',

'algorithms' => 'Donald Knuth',

'PHP' => 'Rasmus Lerdorf',

'architecture' => 'John Von Neumann');


//echo Donald Knuth

$cool_guys = array(




'architecture' => 'John Von Neumann');

echo $cool_guys['algorithms'];

Add an element to an array?

An enumerative array:

$cool_guys[] = 'David Haskins';

-or-

array_push($cool_guys,'David Haskins');


An enumerative array:

$cool_guys[] = 'Jeremy Kendall';

-or-

array_push($cool_guys,'Jeremy Kendall');

(array_push() is slower b/c it's a function call; however you can add many elements at once separated by commas)


An associative array:

$cool_guys['Memphis'] = 'David Haskins';

Update an existing element

Replace Knuth with Dijkstra

Enumerative array:

$cool_guys[1] = 'Edsger Dijkstra';

Associative array:$cool_guys['algorithms'] = 'Edsger Dijkstra';

Remove an existing element

Enumerative array:

unset($cool_guys[1]);

Associative array:unset($cool_guys['algorithms']);

Check if an element exists

Enumerative array:

isset($cool_guys[1]);

Associative array:isset($cool_guys['algorithms']);

View the contents of an array

//let's look at the enumerative array

var_dump($cool_guys);

array(4) {

[0]=>

string(11) 'Alan Turing'

[1]=>

string(12) 'Donald Knuth'

[2]=>

string(14) 'Rasmus Lerdorf'

[3]=>

string(16) 'John Von Neumann'

}

View the contents of an array

//let's look at the enumerative array

print_r($cool_guys);Array

(

[0] => Alan Turing

[1] => Donald Knuth

[2] => Rasmus Lerdorf

[3] => John Von Neumann

)

Multi-dimensional Arrays

What is a multi-dimensional array?

Multi-dimensional Arrays

What is a multi-dimensional array?

A 2-dimensional array is an array that contains another array.

2-dimensional array

$cool_guys = array( 0 => array(

'user' => 'Alan Turing',

'specialty' => 'computer',

'user_id' => 1000),

1 => array(

'user' => 'Donald Knuth',

'specialty' => 'algorithms',

'user_id' => 1001),

2 => array(

'user' => 'Rasmus Lerdorf',

'specialty' => 'PHP',

'user_id' => 1002),

);

print_r($cool_guys);Array

(

[0] => Array

(

[user] => Alan Turing

[specialty] => computer

[user_id] => 1

)

[1] => Array

(

[user] => Donald Knuth

[specialty] => algorithms

[user_id] => 2

)

…snip….

)

var_dump($cool_guys);array(3) {

[0]=>

array(3) {

['user']=>

string(11) 'Alan Turing'

['specialty']=>

string(8) 'computer'

['user_id']=>

int(1)

}

[1]=>

array(3) {

['user']=>

string(12) 'Donald Knuth'

['specialty']=>

string(10) 'algorithms'

['user_id']=>

int(2)

}

…….snip…….

}

Let us assume the following enumerative array:

$cool_guys = array(

'Alan Turing',

'Donald Knuth',

'Rasmus Lerdorf',


Number of elements in an array

$qty = count($cool_guys); // $qty is 4

Iterate over elements in an array

for( $i = 0; $i< count($cool_guys); $i++){

//each cool guy

echo $cool_guys[$i] . ',';

}



//each cool guy


}

Outputs:

Alan Turing, Donald Knuth, Rasmus Lerdorf, John Von Neumann,



//each cool guy


}

Outputs:

Alan Turing, Donald Knuth, Rasmus Lerdorf, John Von Neumann,

Note: you could store the output as a string and rtrim the trailing comma.

Let us assume the following associative array:

$cool_guys = array(




'architectures' => 'John Von Neumann');


foreach($cool_guys as $expertise => $name){

//each cool guy

echo '$name is good at $expertise. \n ';

}


foreach($good_guys as $expertise => $name){

//each cool guy

echo '$name is good at $expertise. \n ';

}

Alan Turing is good at computers.

Donald Knuth is good at algorithms.

Rasmus Lerdorf is good at PHP.

John Von Neumann is good at architectures.

for() vs foreach()

for() and foreach() are not the same thing!

foreach() operates on a copy of the array, not the array itself. If you modify a value in the array, foreach() will not reflect this change in the iteration.

Example

Create a survey in PHP.

Just a form that submits information that is stored in a database.

Ignore sanitization for simplicity.

Example 1

Create two files:• an HTML form• a PHP file to handle form submission

(see example 1)

Example 2

Add more fields…and there may be even more fields to be added at the last minute.

Example 2


There's one problem…

Example 2


There's one problem…

Doing repetitive stuff is boring.

Example 2

Let's use arrays to make life easier.

'The three chief virtues of a programmer are: laziness, impatience and hubris'

- Larry Wall (creator of Perl)

Example 2

$_POST is an array.

Let's take a look at that array.

Example 2print_r($_POST); //placed in submit_form.php

Array (

[first_name] => David

[last_name] => Haskins

[address_1] => 1099 Legacy Farm Court

[address_2] => Apt 202

[city] => Collierville

[state] => Tennessee (TN)

[zip] => 38017

[like_our_product] => wonderful

[like_our_service] => wonderful

[submit] => submit

)

Example 3

Optional, but I like to do it on tiny projects like this.

Put all code in one file.

(check if submitted, and submit to self)

Other things to do with arrays in PHP

Can't remember what order parameters go in?

my_function($user_id,$firm_id,$idx_id);

Other neat things to do with arrays in PHP



Pass an array:

my_function($details);

Other neat things to do with arrays in PHP



Pass an array:

my_function($details);

…and use type hinting to only accept an array:

my_function(Array $details);

Not sure what pre-defined Server variables are available?

(IIS 7, I'm looking at you)

print_r($_SERVER);

Not sure what pre-defined Server variables are available?

(IIS 7, I'm looking at you)

print_r($_SERVER);

also handy if you can't remember:$_SERVER['PHP_SELF'] vs $_SERVER['SCRIPT_NAME'] vs

$_SERVER['SCRIPT_FILENAME'] vs

$_SERVER['URL']…etc.

Treat a string as an enumerative array of chars

$my_str = 'PHP Memphis rocks!';

for($i=0; $i<strlen($my_str); $i++){

echo $my_str[$i] . '-';

}

Treat a string as an enumerative array of chars

$my_str = 'PHP Memphis rocks!';

for($i=0; $i<strlen($my_str); $i++){

echo $my_str[$i] . '-';

}

P-H-P- -M-e-m-p-h-i-s- -r-o-c-k-s-!-

explode()

$product_info = '2012-06-28-314159';

$details = explode('-',$product_info);

print_r($details);

explode()

$product_info = '2012-06-28-314159';

$details = explode('-',$product_info);

print_r($details);

Array ( [0] => 2012

[1] => 06

[2] => 28

[3] => 314159 )

implode()

$my_array = array('a','b','c');

$my_str = implode('_',$my_array);

echo $my_str;

a_b_c

Randomize elements of an array

shuffle($cards);

Use arrays

Hopefully, you will be able to use arrays to manage data in your applications more efficiently.

Look into all of the array functions on PHP.net. There are lots of array sorting, merging, summation, etc. functions available.

Other info on Arrays in PHP

• http://oreilly.com/catalog/progphp/chapter/ch05.html (free chapter!)

• Zend PHP 5 Certification Study Guide

http://oreilly.com/catalog/progphp/chapter/ch05.html



Arrays in PHP

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