1. Web Programming Language
Chapter 5

2. PHP Functions and Objects
Array Functions
Mathematical Functions
Date and Time Functions
Defining Your Own Functions
include and require
Objects in PHP
Creating a Calendar

3. Functions Functions are a key part of coding;
Less typing
Simpler syntax
Fewer errors
Faster loading & execution
Simpler Logic
Without functions, code will quickly grow to a state that is difficult to maintain
PHP has hundreds of functions built in

4. Function Syntax
<?php echo strrev(“.dlroW olleH”); str_repeat(“Hip”, 2); $result = strtoupper(“hooray!”); echo ucfirst(strtolower(“jOhN”)); ?>

5. Array Functions – array()
Used to create an array
<?php $arr = array(“ant”, “bird”, “cat”, “dog”); $arr2 = array(“uk”=>”United Kingdom”, “th”=>”Thailand”, “kh”=>”Cambodia”, “za”=>”South Africa”); ?>

6. Array Functions – print_r()
Outputs array in human readable form
<?php print_r($arr); echo “<br>”; print_r($arr2); ?>

7. Array Functions – array_count_values()
Counts how many times each value occurs in the array, and returns results in a new array.
<?php $arr = array("ant", "bird", "ant", "dog"); print_r(array_count_values($arr)); ?>

8. Array Functions – array_diff() & array_intersect()
Finds differences and similarities between 2 arrays.
<?php $arr = array("ant", "bird", "cat", "dog"); $arr2 = array("ant", "bird", "ant", "dog"); print_r(array_diff($arr, $arr2)); ?>
<?php $arr = array("ant", "bird", "cat", "dog"); $arr2 = array("ant", "bird", "ant", "dog"); print_r(array_intersect($arr, $arr2)); ?>

9. Array Functions – array_flip()
Flips keys and values of an array.
<?php $arr = array("uk"=>"United Kingdom", "th"=>"Thailand", "kh"=>"Cambodia", "za"=>"South Africa"); print_r(array_flip($arr)); ?>

10. Array Functions – in_array() & array_key_exists()
Checks if a value or key is in the array.
<?php $arr = array("uk"=>"United Kingdom", "th"=>"Thailand", "kh"=>"Cambodia", "za"=>"South Africa"); if(in_array("Thailand", $arr)) { echo "That exists!"; } ?>
<?php $arr = array("uk"=>"United Kingdom", "th"=>"Thailand", "kh"=>"Cambodia", "za"=>"South Africa"); if(array_key_exists("th", $arr)) { echo "That exists!"; } ?>

11. Array Functions – array_reverse()
Can you guess what it does?
<?php $arr = array("ant", "bird", "cat", "dog"); print_r(array_reverse($arr)); ?>

12. Array Functions – count()
How many elements in the array – aliased by size_of()
<?php $arr = array("ant", "bird", "cat", "dog"); if(is_array($arr)) { $size = count($arr); //$size == } ?>

13. Array Functions – shuffle()
Randomise the order of elements in the array
<?php $arr = array("ant", "bird", "cat", "dog"); shuffle($arr); print_r($arr); ?>

14. Array Functions - Sorting
There are several ways to sort an array – by key, by value, ascending, descending…
Name
Sort By
Order
Maintain Key=>Value Association
sort()
Value
Low to high No
rsort()
High to low
asort()
Yes
arsort()
ksort()
Key
krsort()

15. Array Functions - Sorting
Examples of each sorting function.
<?php $arr = array("uk"=>"United Kingdom", "th"=>"Thailand", "kh"=>"Cambodia", "za"=>"South Africa"); sort($arr); print_r($arr); ?>

16. Mathematical Functions
There are lots of mathematical functions
abs() – returns absolute value of a number
ceil(), floor() and round() - ceil rounds a number up, floor rounds a number down, round() rounds to a specified number of decimal places
log() and exp() – calculates natural log, and conversely the exponent
max() and min() – return highest or lowest value in an array
pi() – returns pi to 14 decimal places
pow(x,y) – calculates x to the power y
sqrt() – returns the square root
rand() – returns a random number (no longer needing to seed the random number)

17. Trigonometry? Name Performs cos() Cosine cosh() Hyperbolic Cosine
acos()
Arc Cosine
acosh()
Inverse Hyperbolic Cosine
sin()
Sine
sinh()
Hyperbolic Sine
asin()
Arc Sine
asinh()
Inverse Hyperbolic Sine
tan()
Tangent
tanh()
Hyperbolic Tangent
atan()
Arc Tangent
atanh()
Inverse Hyperbolic Tangent

18. Date & Time Functions
Remember that time related functions in PHP are running on the server – which may be located somewhere else from the client machine!
The time() function returns an integer, for the number of seconds since the Unix Epoch – midnight on January 1st 1970 in UTC timezone.
By 2016, there had been 1.4 billion seconds!
PHP offers some functions which make managing time more convenient

19. Date & Time Functions
The date() function reformats the timestamp in many different ways, for example;
<?php echo date("d/m/Y") . "<br>"; //outputs the date for example:- 24/07/ echo date("h:i:sA") . "<br>"; //outputs the time for example:- 01:09:58PM echo date("l jS M, Y") . "<br>"; //outputs a date for example:- Sunday 24th July, ?>
A full list of the different modifying parameters is given on the next slide

20. Date and Time Functions
Character
Description
Example d
2 digit day of the month
01 to 31 D
3 letter text representation of day
Sun to Sat j
Day of month without leading zero
1 to 31 l
Full day name
Sunday to Saturday N
Number of day of the week
1 (Monday), to 7 (Sunday) S
2 character suffix for day of the month
st, th, nd, or rd z
Day of the year
0-365 W
Week number in the year
0-52 F
Name of the month
January – December m
Number of the month
01-12 M
3 letter representation of the month
Jan – Dec n
Number of month, without leading zero
1-12 t
Number of days in the month
28,29,30,31 L
Boolean 1 if a leap year, 0 if not.
1 or 0 Y
4 digit representation of year
2016 or 2001 y
2 digit representation of year
16 or 01 a
Lower case am or pm
am or pm A
Upper case AM or PM
AM or PM g
Hour, in 12 hour format G
Hour, in 24 hour format
0-23 h
Hour, in 12 hour format, with leading zero H
Hour, in 24 hour format, with leading zero
00-23 i
Minutes
00-59 s
Seconds T
Timezone abbreviation
EST, GMT
Date and Time Functions

21. Defining Your Own Functions
The general syntax is:
function functionname(parameter1, parameter2) { //Statements }

22. Returning a Value A value can be returned from the function:
<?php function average($v1, $v2, $v3) { return ($v1 + $v2 + $v3)/3; } ?>

23. Including a Library of Functions
Over time you may wish to move your functions to a separate file, which can be included in your project:
<?php include “functions.php”; ?>

24. include & require
As your code grows it is a good idea to separate different parts of the page into different files
<?php include “functions.php”; include “header.php”; include “navigation.php”; include “side-bar.php”; // Main Content Here include “footer.php”; ?>
Consider with this – if you wanted to make a change to the navigation – you would only need to make a change in one place and it would update every page that includes it.

25. include and require
The difference is when a resource can’t be found – include will return a warning, while require will return a fatal error.

26. Objects in PHP PHP also supports OOP
<?php class fraction { public $num, $denom; function display() { echo $this->num . “/” . $this->denom; } } ?>

27. Objects in PHP The arrow operator is used to access members
<?php $f1 = new fraction; $f1->num = 1; $f1->denom = 2; $f1->display(); ?>
Constructor functions can be created
<?php function __construct() { $this->num = $this->denom = 1; } ?>

28. Calendar Time!
This chapter includes a tutorial for creating a simple, basic calendar. Once you’ve built the basic calendar, use CSS to make it look more attractive. Add links to allow the user to move from month to month. This calendar offers a month view, extend it to add a week view and a day view that users can use to get more details on their screen – make sure your calendar is user friendly, so users can understand how to use it without being taught!