Prepared By : Uday Shah (HOD - IT)
Contact No : 7600044051
E-Mail : rupareleducation@gmail.com
Unit 3: Handling Form, Session Traking & PHP Components in PHP
Explain Cookies
·
Cookies
are text files stored on the client side computer that can each contain around
4000 characters. Up to 20 cookies can store for each website, and the client
computer can store a maximum of 300 cookies in total. Cookie files can be opened
with any text editor so sensitive information should be encrypted.
·
They
are useful to retain user preferences, shopping cart section and other part of
data. For instance, rather than directly store a user’s password in a cookie it
is better to store a unique identification string that references a database
entry containing different cookies. Cookies are located in
C:\document and setting\admin\cookies
·
Cookies
are the temporary storage area where the information is to be stores. The
cookies are seen in the address bar of the browser, history of the websites
visited etc…
·
The
cookies which are created are presented in the local machines.
·
The
activated cookies are stored in the form of text document where in the
information about the cookies name, time of visit etc stored.
·
For an
individual website individual text file is created in local machines.
·
To
create cookie the function setcookie () is used.
Syntax: setcookie(cookie name, cookie value)
To display cookie
(the cookie value ,the global variable $_COOKIE[‘cookie name’]) is used.
Example:
<?php
Setcookie(“Tempcookie”,”cookie will expire in 1
minute”,time() + 60);
echo
$_COOKIE[“tempcookie”];
?>
PHP SESSION
Session is the
temporary storage area where the information is to be stored. The sessions are
used when there is any kind of login.
The login can be
found in any E-mail account, shopping cart, downloading any projects or
software.
Where there is
login there is session. Once the user gets login the username of the user is
developed on each page until the user gets logout.
So entire session
depends on the user, it gets started when the user logins and it gets destroyed
when user logouts.
To create session
two steps are there as shown below:
ð start the session
ð set the value of the session
o To start the session the session_start() is
used.
o To set the session value the global
variable $_SESSION [‘session_name’] is used.
ð Next to display the session, the session
values there are two steps:
o Start the session
o Display using the echo function.
§
Syntax:
echo $_SESSION[‘session_name’];
ð To destroy the session there are 3 steps
o Start session
o Clear the session value
o Destroy the session
§
To
clear the session the function unset is used. Syntax is
unset($_SESSION[‘session_name’])
§
To
destroy the session the function session_destroy() is used.
Example:
Login.php
<?php
$user=”admin”;
$pass=”admin123”;
If($user==”admin” && $pass==”admin123”)
{
session_start();
$_SESSION
[‘username’]=”admin”;
header
(“Location:Next.php”);
}
?>
Example:
Next.php
<?php
session_start();
echo $_SESSION[‘username’].”<a
href=’logout.php’>Logout</a>”;
?>
Ex. Logout.php
<?php
session_start();
unset($_SESSION[‘username’]);
session_destroy();
?>
ð session can be created using session_id()
function. This function either returns the value in the string format. It
returns the arbitrary session_id , If the session is set.
ð Syntax: string session_id([‘session_id’]);
ð The session can also be created using
session_name() function. It is similar to the session id except that it gets or
sets session_name.
ð Syntax: string
session_name([‘session_name’]);
Explain Server Variables
HTTP Cookies :
$_COOKIE:
An associative
array of variables passed to the current script via HTTP cookies. Automatically
global in any scope.
This is a super global or automatic global variable.
This is simply means that it is available in all scope throughout a script.
To access it
within function or method as you do with
$HTTP_COOKIE_VARS.
<?php
Setcookie(“name”,”World”);
Echo “Hello” .htmlspecialchars($_COOKIE[“name”]);
?>
HTTP GET
variables: $_GET:
An associative
array of variables passed to the current script via HTTP get method.
Automatically global in any scope.
This is a
superglobal or automatic global variable. This is simply means that it is
available in all scope throughout a script.
To access it
within function or method as you do with $HTTP_GET_VARS.
<?php
echo
“Hello”.htmlspecialchars($_GET[“name”]);
?>
HTTP POST
variables: $_POST:
An associative
array of variables passed to the current script via HTTP POST method.
Automatically global in any scope.
This is a
superglobal or automatic global variable. This is simply means that it is
available in all scope throughout a script.
To access it
within function or method as you do with $HTTP_POST_VARS.
Ex: <?php
echo
“Hello”.htmlspecialchars($_POST[“name”]);
?>
Request
variables: $_REQUEST:
An associative
array consisting of the contents of $_GET, $_POST and $_COOKIE.
This is a
superglobal or automatic global variable. This is simply means that it is
available in all scope throughout a script.
Global
Variables:$_GLOBALS:
An associative
array containing references to all variables which are currently defined in the
global scope of the script. The variable names are the keys of the array.
Server variables:
$_SERVER:
$_SERVER is an
array containing information such as headers, path and script locations. The
entries in this array are created by the web server. There is no guarantee that
every web server will provide any of these:
To access it within
$_HTTP_SERVER_VARS.
Some of the
server variables are as under.
·
GATEWAY_INTERFACE
·
SERVER_NAME
·
SERVER_SOFTWARE
·
SERVER_PROTOCOL
·
REQUEST_METHOD
·
REQUEST_TIME
·
QUERY_STRINGHTTP_ACCEPT
Explain GD
Library.
·
Php is
a general purpose language used to develop web application with a full featured
database driven web site.
·
The
use of php is suitable for tracking quick development of huge variety of
project along with its extremely each learning curve.
·
PHP
has powerful capabilities for generating images through its popular GD libraries.
·
The
extension has been available for a long time to php developers but quiet
frequently its functionality has been required the web application
implementation dynamically.
·
GD
library comes bundled with both php 4 and php 5 but many web developers do not
take full advantages of its capabilities.
·
It is
extremely useful in the situation where it is necessary to display number of
graphics that need one or more dynamic components.
·
GD it
self can work with a multiple images but when you use with php you can get
information about any GIF,JPEG,SWF,TIFF,BMP,PSD,XBM image format.
·
You
can also manipulate and create images in GIF,JPEG,PNG,WBMP image format.
·
GD can
also allow php to create such as square, polygon and ellipse as well as text
box using true type font.
In GD library
different functions are used like,
·
gd_info():
Used to get the current installed GD library
·
getimagesize()
: to get the size of image
·
imagecreatetruecolor():
used to create a new true color image\
·
imagecolorallocate()
: used to allocate a color for an image
·
imagearc():
used to create an arc image
·
imagepolygon()
:used to draw polygon image
·
imagerectangle():
used to draw rectangle image
·
imagepng()
: used to display png image
·
imagejpeg():
used to display jpeg image
·
imageline():
This function is draws a line between the two given points.
·
Imageellipse():
This function draws an ellipse centered at the specified coordinates.
·
Imagefilledpolygon():
This function creates a filled polygon in the given image.
·
Imagefilledrectangle():
This function creates a filled rectangle with the color in the given image
starting at point 1 and ending at point 2.0,0 is the top left corner of the
image.
·
Imagedestroy():
This function is destroying the image.Returns TRUE on success or false on
failure.
Explain PHP
regular expression:
·
Regular
expression means the formula and general format and any string or expression.
It is used for pattern matching.
·
It is
also known as regexis. Regular expression are used for complex string
manipulation in PHP. It is also used for the validation on server side script.
Advantages:
ð It is portable the data to be entered in
invalid format.
ð It is a portable language as it has general
format.
ð It is easy to learn and use.
Disadvantages:
ð The validation is provided using server
side scripting , which is the main disadvantage because the webpage is refresh
again and again.
There are two
types of regular expression.
1.
POSIX
extended regular expression.
2.
PERL
compatible regular expression.
POSIX extended
regular expression:
When this type of
regular expression is used at that time the ereg() function is required to be
used the pattern matching. This function is returns the length of the match if
the regular expression matches the string. Ereg is abbreviated as Extended
regular expression.
PERL compatible regular expression.
This type is
developed using the PERL language. The function which is used for the given
regular expression is preg() means Perl regular expression.
Explain
uploading a php file.
A php script can
be used with HTML form to allow users to upload files to the server. Initially
files are uploaded into a temporary directory and then relocated to a target
destination by a php script.
Information in the
phpinfo.php page describes the temporary
directory that is used for file uploads as upload_tmp_dir and the
maximum permitted size of the files that can be uploaded is stated as
upload_max_filesize.
The process of
uploading a file follows these steps.
·
The
user open the page containing HTML form featuring text file, a browse button and a submit
button.
·
The
user clicks the browse button and select a file to upload from the local pc.
·
The
full path to the selected file appears in the text then the user clicks on the
submit button
·
The
selected file is sent to the temp. directory on the server.
·
The
php script that was specified as the form handler in the form’s action
attribute that checks the file and then copies the file into an intended
directory.
·
An
uploaded file could be a text file , image file or any document.
Explain How to
sending mail using PHP mail function.
To active the
mail() function for PHP it must be configured correctly in the php.ini file.
Open php.ini file available in directory and find the section headed mail function.
Simply need to let
PHP know the location of their sendmail applications. The path and any desired
switch should be specified to the sendmail_path directive.
PHP provides a
convenient way to send email with the mail() function.
Syntax: mail( to,subject,message, headers,
parameters);
Ex: sending
simple text email using mail()
<?php
$to=”email”;
$subject=”This is subject”;
$message=”This is simple text
message”;
$header=”From:email\r\n”;
$retval=mail($to,$subject,$message,$header);
if($retval==true)
{
echo “Message sent
successfully”;
}
else
{
echo “Message could not be
sent”;
}
?>
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