1. Web Design 2 Using PHP
PHP Arrays

2. Array
An array is a special variable, which can hold more than one value at a time.
In PHP, the array() is used to create an array:
array();
In PHP we have 3 types of arrays:
Indexed arrays - Arrays with a numeric index
Associative arrays - Arrays with named keys
Multidimensional arrays - Arrays containing one or more arrays

3. Integer Indices There <?php $stuff = array("Hi", "There");
echo $stuff[1], "\n";
?>
There

4. Key / Value Web Design 2 <?php $stuff = array("name" => "Chuck",
"course" => “Web Design 2 ");
echo $stuff["course"], "\n";
?>
Web Design 2

5. Dumping an Array
The function print_r() dumps out PHP data - it is used mostly for debugging
<?php
$stuff = array("name" => "Chuck",
"course" => “Web Design 2 ");
echo $stuff["course"], "\n";
?>
Array(
[name] => Chuck
[course] => Web Design 2 )

6. Building up an Array
You can allocate a new item in the array and add a value at the same time using empty square braces [] on the right hand side of an assignment statement
$va = array();
$va[] = "Hello";
$va[] = "World";
print_r($va);
Array(
[0] => Hello
[1] => World )

7. Building up an Array
You can also add new items in an array using a key as well
$za = array();
$za["name"] = "Chuck";
$za["course"] = "PHPIntro";
print_r($za);
Array(
[name] => Chuck
[course] => PHPIntro )

8. Looping Through an Array
<?php
$stuff = array("name" => "Chuck",
"course" => “Web Design 2");
foreach($stuff as $k => $v ) {
echo "Key=",$k," Val=",$v,"\n"; }
?>
Key=name Val=Chuck
Key=course Val= Web Design 2

9. Looping Through an Array
<?php $colors= array(“red", “yellow", “black"); $a_length = count($colors); for($x = 0; $x <  $a_length; $x++) {      echo $colors[$x];      echo "<br>"; } ?>
red
yellow black

10. Arrays of Arrays
$majors = array (
array("archtecural eng","computer eng","telecom eng"),
array("CIS","CS","SE"),
array(" Accounting ","Marketing","Finance"), );
echo " In Engineering: ".$majors[0][0].", ".$majors[0][1].", and, ".$majors[0][2].".<br>";
echo " In IT : ".$majors[1][0].", ".$majors[1][1].", and ".$majors[1][2].".<br>";
echo " In administration sciences: ".$majors[2][0].", ".$majors[2][1].", and ".$majors[2][2].".<br>";
The elements of an array can be many things other than a string or integer. You can even have objects or other arrays.
In Engineering: archtecural eng, computer eng, and, telecom eng. In IT : CIS, CS, and SE. In administration sciences: Accounting, Marketing, and Finance.

11. $course= array(
"IT" => array(
"Java" => "CIS",
"Sql" => "CS"),
"eng" => array(
"autocad"=>"Architectural Eng",
"Alg" => "Computer Eng")
) ;
echo $course["IT"]["Java"];
Arrays of Arrays
The elements of an array can be many things other than a string or integer. You can even have objects or other arrays.
CIS

12. Array Functions count($ar) - How many elements in an array
is_array($ar) - Returns TRUE if a variable is an array
isset($ar['key']) - Returns TRUE if key is set in the array
sort($ar) - Sorts the array values (loses key)
ksort($ar) - Sorts the array by key
asort($ar) - Sorts array by value, keeping key association
shuffle($ar) - Shuffles the array into random order

13. Count: 2 $za Is an array name is set addr is not set $za = array();
$za["name"] = "Chuck";
$za["course"] = “WD2";
print "Count: " . count($za) . "\n";
if ( is_array($za) ) {
echo '$za Is an array' . "\n"; }
else {
echo '$za Is not an array' . "\n";
echo isset($za['name']) ? "name is set\n" : "name is not set\n";
echo isset($za['addr']) ? "addr is set\n" : "addr is not set\n";
Count: 2
$za Is an array
name is set
addr is not set

14. Array(
[name] => Chuck
[course] => WD2
[topic] => PHP )
[0] => Chuck
[1] => PHP
[2] => WD2
$za = array();
$za["name"] = "Chuck";
$za["course"] = “WD2";
$za["topic"] = "PHP";
print_r($za);
sort($za);

15. Array(
[name] => Chuck
[course] => WD2
[topic] => PHP )
$za = array();
$za["name"] = "Chuck";
$za["course"] = “WD2";
$za["topic"] = "PHP";
print_r($za);
ksort($za);
asort($za);

16. PHP array Functions
Visit the following website: Then explore the PHP arrays functions as shown in the next slide.

17. Array Functions:
array_chunk — Split an array into chunks
array_combine — Creates an array by using one array for keys and another for its values
array_column — Return the values from a single column in the input array
array_count_values — Counts all the values of an array
array_diff — Computes the difference of arrays
array_intersect — Computes the intersection of arrays
array_merge — Merge one or more arrays
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_shift — Shift an element off the beginning of array
array_sum — Calculate the sum of values in an array
array_search — Searches the array for a given value and returns the corresponding key if successful
array_reverse — Return an array with elements in reverse order
in_array — Checks if a value exists in an array
what is the difference between:
empty() ,is_null() ,isset() unset()

18. Summary
PHP arrays are a very powerful associative array as they can be indexed by integers like a list, or use keys to look values up like a hash map or dictionary
PHP arrays maintain order and there are many options for sorting