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Diploma in Web Engineering
Module VI: Fundamentals of PHP
Rasan SamarasingheESOFT Computer Studies (pvt) Ltd.No 68/1, Main Street, Pallegama, Embilipitiya.
Contents1. Introduction to PHP2. What PHP Can Do?3. PHP Environment Setup4. What a PHP File is?5. PHP Syntax6. Comments in PHP7. echo and print Statements8. PHP Variables9. PHP Data Types10. Changing Type by settype()11. Changing Type by Casting12. PHP Constants13. Arithmetic Operators14. String Operators15. Assignment Operators16. Comparison Operators17. Logical Operators18. Operators Precedence 19. If Statement20. If… Else Statement
21. If… Else if… Else Statement22. Switch Statement23. The ? Operator24. While Loop25. Do While Loop26. For Loop27. break Statement28. continue Statement29. Functions30. User Defined Functions31. Functions - Returning values32. Default Argument Value33. Arguments as Reference34. Existence of Functions 35. Variable Local and Global Scope36. The global Keyword37. GLOBALS Array38. Superglobals39. Static Variables
Introduction to PHP
• PHP is a server-side scripting language widely used for web development.
• PHP is an acronym for "PHP Hypertext Preprocessor“.
• Originally created by Rasmus Lerdorf in 1994.
• PHP is open source and free to download and use.
What PHP Can Do?
• PHP can generate dynamic page content.• PHP can create, open, read, write, delete, and close
files on the server.• PHP can collect form data.• PHP can send and receive cookies.• PHP can add, delete, modify data in your database.• PHP can restrict users to access some pages on your
website.• PHP can encrypt data.
PHP Environment Setup
Get a web host with PHP and MySQL support
Or
Install a web server on your own PC, and then install PHP and MySQL
What a PHP File is?
• PHP files can contain HTML, CSS, JavaScript, and PHP code.
• PHP files have extension ".php“
• PHP code are executed on the server, and the result is returned to the browser as plain HTML.
PHP Syntax
<html><head><title>PHP Demo</title></head><body>
<?phpecho "Hello World!";?>
</body></html>
index.php
Comments in PHP
// This is a single line comment
# This is also a single line comment
/*This is amultiple linecomment */
echo and print Statements
echo can output one or more stringsecho "Hello world!<br>";echo "Hello”, “ world!”;
print can only output one string, and returns 1print "Hello world!<br>";
PHP Variables
Variables are temporary memory locations storing data
$science = 50;$maths = 60;$total = $science + $maths;echo “Total is: $total”;
PHP Variables
• A variable starts with the $ sign
• A variable name must start with a letter or the underscore character
• A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )
• Variable names are case sensitive
PHP Data Types
• PHP is a Loosely Typed Language
• PHP automatically converts the variable to the correct data type, depending on its value.
• It supports with String, Integer, Floating point, Boolean, Array, Object and NULL data types.
PHP Data types
$pi = 3.14;$week = 7;$name = “Roshan Perera";$city= ‘kandy’;$valid = 10 > 5;
var_dump($pi);var_dump($week);var_dump($name);var_dump($city);var_dump($valid);
Changing Type by settype()
Syntax:settype(mixed var, string type)
Ex:
$x = 3.14;settype($x,"integer");var_dump($x);
Changing Type by Casting
Syntax:var = (datatype) var
Ex:
$x = 3.14;$y = (integer)$x;var_dump($y);
PHP Constants
Once they are defined they cannot be changed
define("GREETING", “Hello world!");echo GREETING;
//Case insensitive constantdefine("GREETING", “Hello world!", true);echo greeting;
Arithmetic Operators
Operator Description Example+ Addition A + B will give 30
- Subtraction A - B will give -10
* Multiplication A * B will give 200
/ Division B / A will give 2
% Modulus B % A will give 0
++ Increment B++ gives 21
-- Decrement B-- gives 19
A = 10, B = 20
String Operators
Operator Name Example
. Concatenation$str1 = "Hello"$str2 = $txt1 . " world!"
.= Concatenation assignment
$str1 = "Hello"$str1 .= " world!"
Assignment Operators
Operator Example
= C = A + B will assign value of A + B into C
+= C += A is equivalent to C = C + A
-= C -= A is equivalent to C = C - A
*= C *= A is equivalent to C = C * A
/= C /= A is equivalent to C = C / A
%= C %= A is equivalent to C = C % A
Comparison Operators
Operator Name Example== Equal (A == B) is false.
=== Identical (A == B) is false.
!= Not equal (A != B) is true.
<> Not equal (A <> B) is true
!== Not identical (A != B) is true.
> Greater than (A > B) is false.
< Less than (A < B) is true.
>= Greater than or equal (A >= B) is false.
<= Less than or equal (A <= B) is true.
A = 10, B = 20
Logical Operators
Operator Name Exampleand And (A and B) is False
or Or (A or B) is True
&& And (A && B) is False
|| Or (A || B) is True
xor Exclusive Or (A xor B) is True
! Not !(A && B) is True
A = True, B = False
Operators Precedence
++, --/, *, %+, -<, <=, >=, >==, ===, !=&&||=, +=, -=, /=, *=, %=, .=andxoror
Prio
rity
If Statement
if(Boolean_expression){ //Statements will execute if the
Boolean expression is true}
Boolean Expression
Statements
True
False
If… Else Statement
if(Boolean_expression){ //Executes when the Boolean expression is
true}else{ //Executes when the Boolean
expression is false}
Boolean Expression
Statements
True
False
Statements
If… Else if… Else Statement
if(Boolean_expression 1){ //Executes when the Boolean expression 1 is true}else if(Boolean_expression 2){ //Executes when the Boolean expression 2 is true}else if(Boolean_expression 3){ //Executes when the Boolean expression 3 is true}else { //Executes when the none of the above condition is true.}
If… Else if… Else Statement
Boolean expression 1
False
Statements
Boolean expression 2
Boolean expression 3
Statements
Statements
False
False
Statements
True
True
True
Switch Statement
switch (value) { case constant: //statements break; case constant: //statements break; default: //statements}
The ? Operator
If condition is true ? Then Value one : Otherwise Value two
$h = 10;$x = $h<12 ? "morning" : "afternoon";
echo $x;
While Loop
while(Boolean_expression){ //Statements}
Boolean Expression
Statements
True
False
Do While Loop
do{ //Statements}while(Boolean_expression);
Boolean Expression
Statements
True
False
For Loop
for(initialization; Boolean_expression; update){ //Statements}
Boolean Expression
Statements
True
False
Update
Initialization
break Statement
Boolean Expression
Statements
True
False
break
continue Statement
Boolean Expression
Statements
True
False
continue
Functions
A function is a block of statements which performing a specific task that can be executed by a call to the function.
Two Categories of Functions:
1. PHP Built-in Functions2. User Defined Functions
User Defined Functions
function functionName(parameters…) { //statements}
functionName(arguments…); //calling function
Functions - Returning values
function functionName(parameters…) { //statements return value;}
//calling function$variableName = functionName(arguments…);
Functions – Default Argument Value
function functionName($parameter = value) { //statements}
functionName(argument); //calling function
functionName(); //calling function without argument
Functions – Arguments as Reference
function functionName(&$parameters…) { //statements}
functionName($arguments…); //calling function
Existence of Functions
function testFunction(){//statements}
$exist = function_exists("testFunction");
var_dump($exist);
Variable Local and Global Scope
$x = 10; // global scope
function testScope() {$y = 20; // local scopeecho "Variable x: $x <br/>";echo "Variable y: $y <br/>";}
testScope();echo "Variable x: $x <br/>";echo "Variable y: $y <br/>";
The global Keyword
$x = 10; // global scope
function testScope() {global $x;$x = 20;}
testScope();echo "Variable x: $x <br/>";
GLOBALS Array
$x = 10; // global scope
function testScope() {$GLOBALS['x'] = 20;}
testScope();echo "Variable x: $x <br/>";
Superglobals
Superglobals are built-in variables that are always available in all scopes.
$GLOBALS$_SERVER$_REQUEST$_POST$_GET$_FILES$_ENV$_COOKIE$_SESSION
Static Variables
function testScope() {static $x = 0;$x++;echo "$x<br/>";}
testScope();testScope();testScope();
The End
http://twitter.com/rasansmn
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