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PHP : Hypertext Preprocessor
What is PHP?
 PHP stands for PHP: Hypertext Preprocessor
 PHP is a widely-used, open source scripting
language
 PHP scripts are executed on the server
 PHP is free to download and use
What is a PHP File?
 PHP files can contain text, HTML, JavaScript code,
and PHP code
 PHP code are executed on the server, and the result
is returned to the browser as plain HTML
 PHP files have a default file extension of ".php"
What Can PHP Do?
 PHP can generate dynamic page content
 PHP can create, open, read, write, 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
Why PHP?
 PHP runs on different platforms (Windows, Linux,
Unix, Mac OS X, etc.)
 PHP is compatible with almost all servers used today
(Apache, IIS, etc.)
 PHP has support for a wide range of databases
 PHP is free. Download it from the official PHP
resource: www.php.net
 PHP is easy to learn and runs efficiently on the
server side
Set Up PHP on Your Own PC
 However, if your server does not support PHP, you
must:
 install a web server
 install PHP
 install a database, such as MySQL
 The official PHP website (PHP.net) has installation
instructions for
PHP: http://php.net/manual/en/install.php
Basic PHP Syntax
A PHP script can be placed anywhere in the
document. A PHP script starts with <?php and ends
with ?>:
<?php
// PHP code goes here
?>
The default file extension for PHP files is ".php".
Comments in PHP
 Example
<html>
<body>
<?php
//This is a PHP comment line
/*
This is a PHP comment
block
*/
?>
</body>
</html>
PHP Variables
 Variable can have short names (like x and y) or more
descriptive names (age, carname, totalvolume).
 Rules for PHP variables:
 A variable starts with the $ sign, followed by the name of
the variable
 A variable name must begin with a letter or the
underscore character
 A variable name can only contain alpha-numeric
characters and underscores (A-z, 0-9, and _ )
 A variable name should not contain spaces
 Variable names are case sensitive ($y and $Y are two
different variables)
Creating (Declaring) PHP Variables
 PHP has no command for declaring a variable.
 A variable is created the moment you first assign a
value to it:
 $txt="Hello world!";
$x=5;
 After the execution of the statements above, the
variable txt will hold the value Hello world!, and the
variable xwill hold the value 5.
 Note: When you assign a text value to a variable,
put quotes around the value.
PHP is a Loosely Typed Language
 In the example above, notice that we did not have to
tell PHP which data type the variable is.
 PHP automatically converts the variable to the
correct data type, depending on its value.
 In a strongly typed programming language, we will
have to declare (define) the type and name of the
variable before using it.
PHP Variable Scopes
 The scope of a variable is the part of the script
where the variable can be referenced/used.
 PHP has four different variable scopes:
 local
 global
 static
 parameter
Local Scope
 A variable declared within a PHP function is local
and can only be accessed within that function:
 Example
<?php
$x=5; // global scope
function myTest()
{
echo $x; // local scope
}
myTest();
?>
Global Scope
 A variable that is defined outside of any function, has
a global scope.
 Global variables can be accessed from any part of
the script, EXCEPT from within a function.
 To access a global variable from within a function,
use the global keyword:
Global Scope
 Example
 <?php
$x=5; // global scope
$y=10; // global scope
function myTest()
{
global $x,$y;
$y=$x+$y;
}
myTest();
echo $y; // outputs 15
?>
Static Scope
 When a function is completed, all of its variables are
normally deleted. However, sometimes you want a
local variable to not be deleted.
 To do this, use the static keyword when you first
declare the variable:
Static Scope
 Example
<?php
function myTest()
{
static $x=0;
echo $x;
$x++;
}
myTest();
myTest();
myTest();
?>
 OUTPUT ?
Parameter Scope
 A parameter is a local variable whose value is
passed to the function by the calling code.
 Parameters are declared in a parameter list as part
of the function declaration:
 Example : <?php
function myTest($x)
{
echo $x;
}
myTest(5);
?>
PHP echo and print Statements
 In PHP there is two basic ways to get output:
echo and print.
 There are some differences between echo and
print:
 echo - can output one or more strings
 print - can only output one string, and returns always 1
 Tip: echo is marginally faster compared to print
as echo does not return any value.
<?php
echo "<h2>PHP is fun!</h2>";
echo "Hello world!<br>";
echo "This", " string", " was", " made", " with multiple
parameters.";
?>
PHP Arrays
 An array stores multiple values in one single
variable:
Example
<?php
$cars = array("Volvo","BMW","Toyota");
echo "I like " . $cars[0] . ", " . $cars[1] . " and " .
$cars[2] . ".";
?>
Create an Array in PHP
• In PHP, the array() function is used to create an
array:
• Example :
$cars = array("Volvo","BMW","Toyota");
• In PHP, there are three types of arrays:
 Indexed arrays - Arrays with numeric index
 Associative arrays - Arrays with named keys
 Multidimensional arrays - Arrays containing one or more
arrays
PHP Indexed Arrays
 There are two ways to create indexed arrays:
 The index can be assigned automatically (index
always starts at 0):
 $cars=array("Volvo","BMW","Toyota");
OR
 The index can be assigned manually:
$cars[0]="Volvo";
$cars[1]="BMW";
$cars[2]="Toyota";
PHP Associative Arrays
 Associative arrays are arrays that use named keys
that you assign to them.
 There are two ways to create an associative array:
 $age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43
");
OR
 $age['Peter']="35";
$age['Ben']="37";
$age['Joe']="43";
PHP Associative Arrays
 Example
<?php
$age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43");
echo "Peter is " . $age['Peter'] . " years old.";
?>
// Output : Peter is 35 years old.
PHP Multidimensional Arrays
 An array can also contain another array as a value,
which in turn can hold other arrays as well. In such a
way we can create two- or three-dimensional arrays:
Example
<?php
// A two-dimensional array:
$cars = array
(
array("Volvo",100,96),
array("BMW",60,59),
array("Toyota",110,100)
);
?>
The foreach Loop
• The foreach loop works only on arrays, and is used to
loop through each key/value pair in an array.
foreach ($array as $value)
{
code to be executed;
}
For every loop iteration, the value of the
current array element is assigned to
$value (and the array pointer is moved by
one) - so on the next loop iteration, you'll
be looking at the next array value.
The foreach Loop
Example:
<?php
$x=array("one","two","three");
foreach ($x as $value)
{
echo $value . "<br>";
}
?>
PHP Functions
 PHP User Defined Functions
 Besides the built-in PHP functions, we can create our own
functions.
 A function is a block of statements that can be used repeatedly in a
program.
 A function will not execute immediately when a page loads.
 A function will be executed by a call to the function.
 Create a User Defined Function in PHP
 A user defined function declaration starts with the word "function":
Syntax
function functionName(arg1, arg2…)
{
code to be executed;
}
 Note: A function name can start with a letter or underscore (not a
number).
GET Vs POST
PHP $_GET Variable
• The predefined $_GET variable is used to collect
values in a form with method="get"
• Information sent from a form with the GET method is
visible to everyone (it will be displayed in the
browser's address bar) and has limits on the amount
of information to send.
• Example
<form action="welcome.php" method="get">
Name: <input type="text" name="fname">
Age: <input type="text" name="age">
<input type="submit">
</form>
• When the user clicks the "Submit" button, the URL sent
to the server could look something like this:
http://www.w3schools.com/welcome.php?fname=Peter&age=37
• The "welcome.php" file can now use the $_GET variable
to collect form data as follow:
Welcome <?php echo $_GET["fname"]; ?>.<br>
You are <?php echo $_GET["age"]; ?> years old!
The $_POST Variable
• The predefined $_POST variable is used to collect
values from a form sent with method="post".
• Information sent from a form with the POST method
is invisible to others and has no limits on the amount
of information to send.
• Note: However, there is an 8 MB max size for the
POST method, by default (can be changed by
setting the post_max_size in the php.ini file).

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Introduction to php

  • 1. PHP : Hypertext Preprocessor
  • 2. What is PHP?  PHP stands for PHP: Hypertext Preprocessor  PHP is a widely-used, open source scripting language  PHP scripts are executed on the server  PHP is free to download and use
  • 3. What is a PHP File?  PHP files can contain text, HTML, JavaScript code, and PHP code  PHP code are executed on the server, and the result is returned to the browser as plain HTML  PHP files have a default file extension of ".php"
  • 4. What Can PHP Do?  PHP can generate dynamic page content  PHP can create, open, read, write, 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
  • 5. Why PHP?  PHP runs on different platforms (Windows, Linux, Unix, Mac OS X, etc.)  PHP is compatible with almost all servers used today (Apache, IIS, etc.)  PHP has support for a wide range of databases  PHP is free. Download it from the official PHP resource: www.php.net  PHP is easy to learn and runs efficiently on the server side
  • 6. Set Up PHP on Your Own PC  However, if your server does not support PHP, you must:  install a web server  install PHP  install a database, such as MySQL  The official PHP website (PHP.net) has installation instructions for PHP: http://php.net/manual/en/install.php
  • 7. Basic PHP Syntax A PHP script can be placed anywhere in the document. A PHP script starts with <?php and ends with ?>: <?php // PHP code goes here ?> The default file extension for PHP files is ".php".
  • 8. Comments in PHP  Example <html> <body> <?php //This is a PHP comment line /* This is a PHP comment block */ ?> </body> </html>
  • 9. PHP Variables  Variable can have short names (like x and y) or more descriptive names (age, carname, totalvolume).  Rules for PHP variables:  A variable starts with the $ sign, followed by the name of the variable  A variable name must begin with a letter or the underscore character  A variable name can only contain alpha-numeric characters and underscores (A-z, 0-9, and _ )  A variable name should not contain spaces  Variable names are case sensitive ($y and $Y are two different variables)
  • 10. Creating (Declaring) PHP Variables  PHP has no command for declaring a variable.  A variable is created the moment you first assign a value to it:  $txt="Hello world!"; $x=5;  After the execution of the statements above, the variable txt will hold the value Hello world!, and the variable xwill hold the value 5.  Note: When you assign a text value to a variable, put quotes around the value.
  • 11. PHP is a Loosely Typed Language  In the example above, notice that we did not have to tell PHP which data type the variable is.  PHP automatically converts the variable to the correct data type, depending on its value.  In a strongly typed programming language, we will have to declare (define) the type and name of the variable before using it.
  • 12. PHP Variable Scopes  The scope of a variable is the part of the script where the variable can be referenced/used.  PHP has four different variable scopes:  local  global  static  parameter
  • 13. Local Scope  A variable declared within a PHP function is local and can only be accessed within that function:  Example <?php $x=5; // global scope function myTest() { echo $x; // local scope } myTest(); ?>
  • 14. Global Scope  A variable that is defined outside of any function, has a global scope.  Global variables can be accessed from any part of the script, EXCEPT from within a function.  To access a global variable from within a function, use the global keyword:
  • 15. Global Scope  Example  <?php $x=5; // global scope $y=10; // global scope function myTest() { global $x,$y; $y=$x+$y; } myTest(); echo $y; // outputs 15 ?>
  • 16. Static Scope  When a function is completed, all of its variables are normally deleted. However, sometimes you want a local variable to not be deleted.  To do this, use the static keyword when you first declare the variable:
  • 17. Static Scope  Example <?php function myTest() { static $x=0; echo $x; $x++; } myTest(); myTest(); myTest(); ?>  OUTPUT ?
  • 18. Parameter Scope  A parameter is a local variable whose value is passed to the function by the calling code.  Parameters are declared in a parameter list as part of the function declaration:  Example : <?php function myTest($x) { echo $x; } myTest(5); ?>
  • 19. PHP echo and print Statements  In PHP there is two basic ways to get output: echo and print.  There are some differences between echo and print:  echo - can output one or more strings  print - can only output one string, and returns always 1  Tip: echo is marginally faster compared to print as echo does not return any value. <?php echo "<h2>PHP is fun!</h2>"; echo "Hello world!<br>"; echo "This", " string", " was", " made", " with multiple parameters."; ?>
  • 20. PHP Arrays  An array stores multiple values in one single variable: Example <?php $cars = array("Volvo","BMW","Toyota"); echo "I like " . $cars[0] . ", " . $cars[1] . " and " . $cars[2] . "."; ?>
  • 21. Create an Array in PHP • In PHP, the array() function is used to create an array: • Example : $cars = array("Volvo","BMW","Toyota"); • In PHP, there are three types of arrays:  Indexed arrays - Arrays with numeric index  Associative arrays - Arrays with named keys  Multidimensional arrays - Arrays containing one or more arrays
  • 22. PHP Indexed Arrays  There are two ways to create indexed arrays:  The index can be assigned automatically (index always starts at 0):  $cars=array("Volvo","BMW","Toyota"); OR  The index can be assigned manually: $cars[0]="Volvo"; $cars[1]="BMW"; $cars[2]="Toyota";
  • 23. PHP Associative Arrays  Associative arrays are arrays that use named keys that you assign to them.  There are two ways to create an associative array:  $age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43 "); OR  $age['Peter']="35"; $age['Ben']="37"; $age['Joe']="43";
  • 24. PHP Associative Arrays  Example <?php $age=array("Peter"=>"35","Ben"=>"37","Joe"=>"43"); echo "Peter is " . $age['Peter'] . " years old."; ?> // Output : Peter is 35 years old.
  • 25. PHP Multidimensional Arrays  An array can also contain another array as a value, which in turn can hold other arrays as well. In such a way we can create two- or three-dimensional arrays: Example <?php // A two-dimensional array: $cars = array ( array("Volvo",100,96), array("BMW",60,59), array("Toyota",110,100) ); ?>
  • 26. The foreach Loop • The foreach loop works only on arrays, and is used to loop through each key/value pair in an array. foreach ($array as $value) { code to be executed; } For every loop iteration, the value of the current array element is assigned to $value (and the array pointer is moved by one) - so on the next loop iteration, you'll be looking at the next array value.
  • 27. The foreach Loop Example: <?php $x=array("one","two","three"); foreach ($x as $value) { echo $value . "<br>"; } ?>
  • 28. PHP Functions  PHP User Defined Functions  Besides the built-in PHP functions, we can create our own functions.  A function is a block of statements that can be used repeatedly in a program.  A function will not execute immediately when a page loads.  A function will be executed by a call to the function.  Create a User Defined Function in PHP  A user defined function declaration starts with the word "function": Syntax function functionName(arg1, arg2…) { code to be executed; }  Note: A function name can start with a letter or underscore (not a number).
  • 30. PHP $_GET Variable • The predefined $_GET variable is used to collect values in a form with method="get" • Information sent from a form with the GET method is visible to everyone (it will be displayed in the browser's address bar) and has limits on the amount of information to send. • Example <form action="welcome.php" method="get"> Name: <input type="text" name="fname"> Age: <input type="text" name="age"> <input type="submit"> </form>
  • 31. • When the user clicks the "Submit" button, the URL sent to the server could look something like this: http://www.w3schools.com/welcome.php?fname=Peter&age=37 • The "welcome.php" file can now use the $_GET variable to collect form data as follow: Welcome <?php echo $_GET["fname"]; ?>.<br> You are <?php echo $_GET["age"]; ?> years old!
  • 32. The $_POST Variable • The predefined $_POST variable is used to collect values from a form sent with method="post". • Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send. • Note: However, there is an 8 MB max size for the POST method, by default (can be changed by setting the post_max_size in the php.ini file).