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What is php
PHP = PHP: Hypertext Preprocessor | Server-
side scripting language that may be embedded into
HTML | Ultimate goal is to get PHP files to generate
client side code | must end up with HTML, CSS,
JavaScript, other client .
:

SIDE BY SIDE
PHP FILE HTML FILE OUTPUT
<head> <Head>
<Title introducing php < /Title> <title introducing php< /title>
<Body> <body
<?php HELLO WORLD
ECHO HELLO WORLD </body>
?> Print(output)
</Body> HELLO WORLD

Introducing php
PHP TAG’S
Single line comment (//)
Multiple line comment (/* and /*)
The echo command

VIEWING PHP FILE
PHP files executed on the web server
_| Therefore we cannot save them anywhere and view them, as with HTML files
_| Must save .php files in subdirectory of web server
var/www/ on many Linux configurations
_| www directory of your user directory on Athena
_| Make call to web server via domain name (google.com), IP address (127.0.0.1), or
localhost
if on your own computer

PHP
Syntax: Variables,
Operators, and Strings

VARIABLE'S
Store values for future reference, use variable name to refer to the
value stored in it PHP is a loosely-typed language Do not need to
declare the type of a variable
Type can change throughout the program $x = 42:
//
store the value 42 in $x echo $x; // prints 42 echo $x+1; // prints
43, value of $x is still 42 $x = ‘hello!’ // type of $x can change

OPRATER'S
Arithmetic operators
+,-,*/,% (modulus - remainder after division)
Logical AND (&&), OR (||), NOT (!)
Assignment operators Shorthand for assignment operators: $x +=
$y equivalent to $x = $x + $y Also works with subtraction,
multiplication, division, modulus, and string concatenation

● VERSUS
Two “equality” operator == tests for “equality” in
value but not necessarily
type === tests for “identity” in value AND type ==
ignores the distinction between: Integers, floating
point numbers, and strings containing the same
numerical value Nonzero numbers and boolean
TRUE
Zero and boolean FALSE

STRING'S
A sequence of characters Single and double quotes: suppose $str = 42;
“| echo ‘With single quotes, str is $str’; 7 output:
With single quotes, str is $str ~ echo “With double quotes, str is $str’; ~
output: With double quotes, str is 42

STRING'S
Col icatenation of rings - the . operator | String aie ictions 7
Length: strlen() | Position of substring: strpos()
_ More on string functions:
http://www.w3schools.com/php/php_ref_string.asp $a
=‘hello; pb = = ‘wor rid’; echo $a.‘‘. $b.‘!’: // prints ‘hello
world!’

CONDITIONAL STATEMENTS
if (condition / boolean expression) { statements
else if (another condition) { statements
// there may be more than one else if block else { statements
$x = 5; if(Sx*=5){ echo ‘The variable x has value 5!’:

THE WHILE LOOP
while (condition) { statements } x <
1000) { echo $x. “n”: //is newline character
$x = $x * $x;

THE DO WHILE LOOP
The code within the loop is executed at least once,
regardless of ae = condition is true O statements }
while (condition); equivalent to: statements while
(condition) { statements

CONDITIONAL STATEMENTS
if (condition / boolean expression) { statements
else if (another condition) { statements
// there may be more than one else if block
else { statements
} = 5; a ){
echo ‘The variable x has value 5!:

THE WHILE LOOP
while (condition) { statements j x < 1000) { echo
$x.“n’; //newline character
$x = $x * $x;

THE DO WHILE LOOP
The code within the loop is executed at least once,
regardless of whether the condition is true do {
statements } while (condition); equivalent to:
statements while (condition) { statements

THE FOR LOOP
for (init; condition; increment) {
ie Cae equivalent to: init while (condition) { statements
increment
Prints the first 10 positive integers and their squares:
f i= 1; $i <= 10; $i a ae * ¢i) ir)
} Defining your fucation
function function_name ($arg1, $arg2) { function code return $var //optional } True funcation
Example: a simple multiply function
function Re { x * $y;
echo echo “”: multiply(5, 1.2); 2 prints 6 $a=5; Sip.
error a, $b); 7 prints O (?!)

RETURN VALUE'S
“| A function can return a value after it is done
_| Use this value in future computation, use like a variable, assign value to a variable
A modified multiply function
function multiply($x, $y) {
return $x * $y;
j
multiply(2,3); 3 prints nothing! returns value, but we don’t store anywhere echo multiply(2,3); © prints 6
$a = multiply(2,3); 0 assigns the value 6 to the variable $a
$b = multiply(multiply(2,3), multiply(3,4)); © assigns the value 72 to the variable $b

RETURN VALUE'S
puecten can return at most once, and it can only return one value
| If it does not return anything, assignments will result in NULL _| A function ends after it returns, even if there
is code following the return statement
function do_stuff($x) {
if ($x % 2 == 0) { //if even
return $x/2 // exits function at this point
}
// this is ONLY executed if x is odd $x += 5;
if ($x < 10) {
$x += 3;

MAKING FUNCATION CALL
Code inside of a function is not executed unless the function is called.
‘Code outside of functions is executed whenever the program is
executed. ‘ <2PHP
.. // some code function1(): // makes function call to functioni(), which
/finturn calls function3() function function1() { .. // some code
function3(): // makes function call to function3()
function functiona() { // this function is never called! . // some code
function function3() { i # some code

Arry as alist of elements
Use arrays to keep track of a list of elements using the same variable
name, identifying each element by its index, starting with O
$colors = array(‘red’, ‘blue’, ‘green’, ‘black’, ‘yellow’; To add an element to
the array:
$colors[] = ‘purple’;
© Toremove an element from the array: unset($colors[2]); colors); Recap
:arrays
print_r($array_name) function lets you easily

RECAP:ARRAY
View the contents of an array
PHP arrays as alist PHP arrays as a map $favorite_colors =
array(‘Joe => ‘blue’, ‘Elena’ => ‘green’, ‘Mark’ => ‘brown’,
‘Adrian’ => ‘black’, ‘Charles’ => ‘red’): colors[‘Adrian’]):
$colors = array(‘red’, ‘blue’, ‘green’, ‘black’, ‘yellow’;
colors[1]): colors); All

All arrays are associative
Each element in an array will have a unique key,
whether you specify it or not.
EXAMPLE $colors = array(‘red’, ‘blue’, ‘green’, ‘black’,
‘yellow);
print_ pacolers gives: Array( 3 =>red => blue tae reen =>
black [4] => yellow

For each loop
The for-each loops allow for easy iteration over all elements of an array.
foreach ($array_name as $value) { code here
foreach ($array_name as $key => $value) { code here
foreach ($colors as $color) { echo $color; // simply prints each color
foreach ($colors as $number => color) {
echo “$number => $color’”; // prints color with index // to change an element:
// number] = $new_color

When to use $ get vs.$_post
1.GET requests are sent via the URL, and can thus be
cached, bookmarked, shared, etc
2.GET requests are limited by the length of the URL
3. POST requests are not exposed in the URL and should be used for
sensitive data
4. There is no limit to the amount of information
passed via _POST

FORMS:SERVER-SIDE
A simple PHP file that displays what was entered into the form
Can do many other things server-side depending on the situation
Note the use of $ _POST

COOKIES AND SESSIONS
HTTP is stateless — it does not keep track of the client between requests
But sometimes we need to keep track of this information
Shopping cart | “Remember me’ on login sites | 2 solutions to this issue ~ Cookies -
small file stored client-side _ Sessions - relevant data stored on the server

EXAMPLE OF COOKIES USAGE
Main disadvantages of cookies
_| Limited in size by browser
_] Stored client-side ~ can be tampered with
_| Sessions store user data on the server
_| Limited only by server space
-| Cannot be modified by users
_| A potential downside to sessions is that they expire
when the browser Is closed
_ Sessions are identified by a session Id: often a small cookie! But the rest of the data is still stored on the server. Using
session

Using session
Call session_start() at top of every page to start session U Sets a cookie on the
client: must follow same rules as cookies (before any HTML, CSS, JS, echo or print
statements)
0 Access data using the $_ SESSION superglobal, just like $ COOKIE, $_GET, or
$_POST

Using session
<?php {
Session start () $session [“count”]==1;
If(isset($session ([“count”]))); echo “you visited once “;
{ }
$session [“count”]=1; ?>
Echo “visited here”;
{
Else

Indore Institute of Computer Education (IICE)
http://www.iiceducation.in/
IICE (Indore Institute of Computer Education) is the leading training institute in Indore, India. We have developed ourselves into
a well-known brand in the education sector of the country. We offer a wide range of courses that are designed to provide a
well-rounded education to the students so that they can gain a competitive edge in the current job markets.

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