Post on 05-Dec-2014
description
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
A data type is a set of data (information) with certain characteristics.
PHP has: Primitive data types• Booleans (true,false)• Integers • Floating point numbers• Strings• Arrays • Objects
Data types
A data type is a set of data (information) with certain characteristics.
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
A data type is a set of data (information) with certain characteristics.
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
A data type is a set of data (information) with certain characteristics.
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
A data type is a set of data (information) with certain characteristics.
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 ($_SERVER, $user = new array()…)• Objects
Data types
A data type is a set of data (information) with certain characteristics.
PHP has: Primitive data types & Composite data types
• Booleans (true,false)• Integers (…-2,-1,0,1,2,3,4,5…)• Floating point numbers (3.14159,2.71828…)• Strings ('Memphis', 'Meetup Group'…)• Arrays ($_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();
How do you create an array?
//create a populated array
$cool_guys = array(
'Alan Turing',
'Donald Knuth',
'Rasmus Lerdorf',
'John Von Neumann');
How do you create an array?
//echo Donald Knuth
$cool_guys = array(
'Alan Turing',
'Donald Knuth',
'Rasmus Lerdorf',
'John Von Neumann');
echo $cool_guys[1];
How do you create an array?
//create a populated associative array
$cool_guys = array(
'computers' => 'Alan Turing',
'algorithms' => 'Donald Knuth',
'PHP' => 'Rasmus Lerdorf',
'architecture' => 'John Von Neumann');
How do you create an array?
//echo Donald Knuth
$cool_guys = array(
'computers' => 'Alan Turing',
'algorithms' => 'Donald Knuth',
'PHP' => 'Rasmus Lerdorf',
'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');
Add an element to an array?
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)
Add an element to an array?
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',
'John Von Neumann');
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] . ',';
}
Iterate over elements in an array
for( $i = 0; $i< count($cool_guys); $i++){
//each cool guy
echo $cool_guys[$i] . ',';
}
Outputs:
Alan Turing, Donald Knuth, Rasmus Lerdorf, John Von Neumann,
Iterate over elements in an array
for( $i = 0; $i< count($cool_guys); $i++){
//each cool guy
echo $cool_guys[$i] . ',';
}
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:
$cool_guys = array(
'computers' => 'Alan Turing',
'algorithms' => 'Donald Knuth',
'PHP' => 'Rasmus Lerdorf',
'architectures' => 'John Von Neumann');
Iterate over elements in an array
foreach($cool_guys as $expertise => $name){
//each cool guy
echo '$name is good at $expertise. \n ';
}
Iterate over elements in an array
foreach($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
Add more fields…and there may be even more fields to be added at the last minute.
There's one problem…
Example 2
Add more fields…and there may be even more fields to be added at the last minute.
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,$idx_id);
Other neat things to do with arrays in PHP
Can't remember what order parameters go in?
my_function($user_id,$firm_id,$idx_id);
Pass an array:
my_function($details);
Other neat things to do with arrays in PHP
Can't remember what order parameters go in?
my_function($user_id,$firm_id,$idx_id);
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