PHP Forms,sessions and file handling with example

PHP Forms,sessions and file handling with example

• 2.
  Form Processing • Wecan access form data using there inbuilt PHP associative array. • $_GET => in case we have used get method in the form • $_POST => in case we have used post method in the form • $_REQUEST => in both the cases • For example, html <form action=“recive.php” method=“get”> <input type=“text” name=“UserName”> <input type=“submit”> </form> recive.php <?php $u = $_GET[‘UserName’]; echo($u); ?>
• 3.
  File Handling inPHP • PHP has several functions for creating, reading, uploading, and editing files. • fopen($filename, $mode) will return the handle to access file. • "r" (Read only. Starts at the beginning of the file) • "r+" (Read/Write. Starts at the beginning of the file) • "w" (Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist) • "w+" (Read/Write. Opens and clears the contents of file; or creates a new file if it doesn't exist) • "a" (Write only. Opens and writes to the end of the file or creates a new file if it doesn't exist) • "a+" (Read/Write. Preserves file content by writing to the end of the file)
• 4.
  File Handling inPHP (Cont.) Function Purpose file_exists($file) Will return true if file is found, false otherwise filesize($file) Returns the size of the file in bytes. fread($file,$bytesToRead) Will read $bytesToRead from $file handle fwrite($file,$str) Will write $str in the $file handle fclose($file) Will close the $file handle copy($source,$destination) Will copy from $source to $destination rename($oldname,$newname) Will rename the file to $newname unlink($file) Will delete the file
• 5.
  File Handling Example ReadFile <?php $file = fopen("text.txt","a+"); $text = fread($file,filesize("text.txt")); echo($text); ?> Write File <?php fwrite($file," New Content"); $text = fread($file,filesize("text.txt")); echo($text); ?> text.txt Hello World From Darshan College
• 6.
  Cookies in PHP •HTTP cookies are data which a server-side script sends to a web client to keep for a period of time. • On every subsequent HTTP request, the web client automatically sends the cookies back to server (unless the cookie support is turned off). • The cookies are embedded in the HTTP header (and therefore not visible to the users). • Shortcomings/disadvantages of using cookies to keep data • User may turn off cookies support. • Users using the same browser share the cookies. • Limited number of cookies (20) per server/domain and limited size (4k bytes) per cookie • Client can temper with cookies
• 7.
  Cookies in PHP(Cont.) • To set a cookie, call setcookie() • e.g., setcookie('username', ‘AVB'); • To delete a cookie (use setcookie() without a value) • e.g., setcookie('username'); • To retrieve a cookie, refer to $COOKIE • e.g. $username = $_COOKIE['username‘]; • Note : • Cookies can only be set before any output is sent. • You cannot set and access a cookie in the same page. Cookies set in a page are available only in the future requests.
• 8.
  Cookies in PHP(Cont.) setcookie(name, value, expiration, path, domain, secure, httponly) • Expiration • Cookie expiration time in seconds • 0  The cookie is not to be stored persistently and will be deleted when the web client closes. • Negative value  Request the web client to delete the cookie • e.g.: setcookie('username', 'Joe', time() + 1800); // Expire in 30 minutes • Path • Sets the path to which the cookie applies. (Default is ‘/’) • Domain • The domain that the cookie is available. • Secure • This can be set to 1 to specify that the cookie should only be sent by secure transmission using HTTPS otherwise set to 0 which mean cookie can be sent by regular HTTP.
• 9.
  Session in PHP •Session is a way to make data accessible across the various pages of an entire website is to use a PHP Session. • A session creates a file in a temporary directory on the server where registered session variables and their values are stored. • The location of the temporary file is determined by a setting in the php.ini file called session.save_path. • When a session is started following things happen • PHP first creates a unique identifier for that particular session which is a random string of 32 hexadecimal numbers such as 3c7foj34c3jj973hjkop2fc937e3443. • A cookie called PHPSESSID is automatically sent to the user's computer to store unique session identification string. • A file is automatically created on the server in the designated temporary directory and bears the name of the unique identifier prefixed by sess_, sess_3c7foj34c3jj973hjkop2fc937e3443.
• 10.
  Starting a PHPSession • A PHP session is easily started by making a call to the session_start() function.This function first checks if a session is already started and if none is started then it starts one. • It is recommended to put the call to session_start() at the beginning of the page. • The following example starts a session then register a variable called counter that is incremented each time the page is visited during the session.
• 11.
  • <?php • session_start(); •if( isset( $_SESSION['counter'] ) ) { • $_SESSION['counter'] += 1; • }else { • $_SESSION['counter'] = 1; • } • $msg = "You have visited this page ". $_SESSION['counter']; • $msg .= "in this session."; • ?> • <html><head> • <title>Setting up a PHP session</title> • </head><body> • <?php echo ( $msg ); ?> • </body></html>
• 12.
  Destroying a PHPSession • A PHP session can be destroyed by session_destroy() function. • This function does not need any argument and a single call can destroy all the session variables. • If you want to destroy a single session variable then you can use unset() function to unset a session variable. Logout.php <?php session_destroy(); ?> Logout.php <?php unset(S_SESSION[‘counter’]); ?>
• 13.
  Object Oriented Concepts •Classes, which are the "blueprints" for an object and are the actual code that defines the properties and methods. • Objects, which are running instances of a class and contain all the internal data and state information needed for your application to function. • Encapsulation, which is the capability of an object to protect access to its internal data • Inheritance, which is the ability to define a class of one kind as being a sub- type of a different kind of class (much the same way a square is a kind of rectangle). • Polymorphism, which means that, depending on the circumstances, an object will act diffrently.
• 14.
  Creating Class • Let'sstart with a simple example. Save the following in a file called MyClass.php: MyClass.php <?php class Demo { // Code Here } ?>
• 15.
  Adding Method • TheDemo class isn't particularly useful if it isn't able to do anything, so let's look at how you can create a method. MyClass.php <?php class Demo { function SayHello($name) { echo “Hello $name !”; } } ?>
• 16.
  Adding Properties • Addinga property to your class is as easy as adding a method. • There are three different levels of visibility that a member variable or method can have : • Public : members are accessible to any and all code (Default) • Private : members are only accessible to the class itself • Protected : members are available to the class itself, and to classes that inherit from it MyClass.php <?php class Demo{ public $name; function SayHello($name){ echo “Hello $name !”; } } ?>
• 17.
  Constructor / Destructor •Constructor is the method that will be implemented when object has been initiated, Commonly, constructor is used to initialize the object • Use function __construct (also referred as Magic Function) to create constructor in PHP MyClass.php <?php class Demo{ function __construct { } function __destruct { } } ?>
• 18.
  Inheritance Human.php <?php class Human{ private $name= “a”; public function getName() { return $this->name; } } ?> Student.php <?php class Student extends Human{ private $rollno = “001”; public function getRoll() { return $this->rollno; } } ?> Faculty.php <?php class Faculty extends Human{ private $staffInitial = “abc”; public function getInitial() { return $this->staffInitial; } } ?> My.php <?php $mystu = new Student(); $mystu->getRoll(); $mystu->getName(); $myfac = new Faculty(); $myfac->getName(); $myfac->getInitial(); ?>