1. 15 – PHP(5) Informatics Department Parahyangan Catholic University

2.  Sometimes we need to work with zip files, for example:  compressing several files to be downloaded at once  uncompressing a zip file that the user uploaded  etc.  PHP version 5.2 and later comes with ZipArchive class

3.  To create a new archive, first create an object of ZipArchive class:  Then we open the new archive with the open() method: $zip = new ZipArchive(); $filename = "abc.zip"; if ($zip->open($filename, ZipArchive::CREATE)!==TRUE) { exit("cannot open $filename\n"); }

4.  There are 4 modes available when opening an archive:  ZipArchive::OVERWRITE Always start a new archive, this mode will overwrite the file if it already exists.  ZipArchive::CREATE Opens an existing zip file, or create a new archive if it does not exist.  ZipArchive::EXCL Error if archive already exists.  ZipArchive::CHECKCONS Perform additional consistency checks on the archive, and error if they fail (eg. broken zip, corrupted upload, etc.)

5.  The addFile() method adds a file to an opened archive  The close() method closes the active archive and saves changes $zip->addFile("Document1.txt"); $zip->addFile("Document2.txt"); $zip->addFile("Document3.txt"); $zip->close();

6.  The addFile() method can give a new name for the added file by providing the second argument  Example: $zip->addFile("Document1.txt", "File 1.txt"); $zip->addFile("Document2.txt", "File 2.txt"); $zip->addFile("Document3.txt", "File 3.txt");

7.  Several useful attributes/methods:  numFiles attribute the number of files contained in the active archive file  filename attribute the complete path of the active archive file  statIndex() method Get the details of an entry defined by its index  statName() method Get the details of an entry defined by its name  setPassword() method Set a password for opening an archive

8.  Example: $zip = new ZipArchive(); $filename = "abc.zip"; if ($zip->open($filename) != TRUE) { exit("cannot open \n"); } echo "numFiles: ". $zip->numFiles. " "; echo "filename: ". $zip->filename. " "; for ($i=0; $i numFiles;$i++) { $current = $zip->statIndex($i); echo "index $i : "; printf("%s (size: %d byte(s)) ", $current["name"], $current["size"]); } when open() is used without the second parameter, it tries to open an existing zip file, returning FALSE when the file doesn’t exist

9.  Example:

10.  The extractTo() method extracts the complete archive or the given files to the specified destination.  Syntax: bool extractTo(string $destination [, mixed $entries]) single entry name or array of names

11.  Example:  extracts the complete archive  extracts one file  extracts an array of files $destination = "extracted/abc"; $zip->extractTo($destination); $destination = "extracted/abc"; $zip->extractTo($destination, "Document1.txt"); $destination = "extracted/abc"; $zip->extractTo($destination, array("Document1.txt", "Document2.txt"));

12.  The addEmptyDir() method adds an empty directory in the archive  Example: $zip->addEmptyDir("newDir1"); $zip->addFile("Document1.txt", "newDir1/Document1.txt"); $zip->addEmptyDir("newDir2"); $zip->addFile("Document2.txt", "newDir2/Document2.txt"); Unix / Windows Compatibility When specifying a path on Unix platforms, a forward slash (/) is used as directory separator. On Windows platforms, both forward slash (/) and backslash (\) can be used. Unix / Windows Compatibility When specifying a path on Unix platforms, a forward slash (/) is used as directory separator. On Windows platforms, both forward slash (/) and backslash (\) can be used.

13.  The Directory class allow us to retrieve information about directories and their contents.  Instances of Directory are created by calling the dir() function, not by the new operator.  The getcwd() function returns a string containing the current working directory.

14.  The read() method returns the name of the next entry in the directory. The entries are returned in the order in which they are stored by the file system.  The close() method closes the previously opened directory handle

15.  Example: $d = dir(getcwd()); echo "Path: ". $d->path. " "; while (($file = $d->read()) !== false){ echo "filename: ". $file. " "; } $d->close();

16.  Example:

17.  Example: processing.txt files only $d = dir(getcwd()); echo "Path: ". $d->path. " "; while (($file = $d->read()) !== false){ if(pathinfo($file, PATHINFO_EXTENSION) == "txt") echo $file. " "; } $d->close();

18.  The is_dir() function tells whether the given filename is a directory  Example: processing directory only $d = dir(getcwd()); echo "Path: ". $d->path. " "; while (($file = $d->read()) !== false){ if(is_dir($file)) echo $file. " "; } $d->close();

19.  The addFile() method adds a single file to a zip archive. To zip an entire directory, we need to recursively iterate all the directories and adds all the files one by one.  One implementation by Ramui can be found here: http://ramui.com./articles/php-zip-files-and- directory.html http://ramui.com./articles/php-zip-files-and- directory.html

21.  Class definitions contain the class name (which is case-sensitive), its attributes, and its methods.  Example: class User{ public $name; public $password; function User($param1, $param2){ $this->name=$param1; $this->password=$param2; } function save_user(){ echo "Save User code goes here"; }

22.  To create an object with a specified class, use the new keyword  Example:  $object = new User;  $temp = new User('name', 'password');

23.  To access object’s attribute: $object->attribute  To access object’s method: $object->method()  The property and method names do not have dollar signs ( $ ) in front of them.

24.  Once you have created an object, it is passed by reference when you pass it as a parameter.  In other words, making object assignments does not copy objects in their entirety.  Example: this prints “Wombaty” $u1 = new User("Wombat", "womwom"); $u2 = $u1; $u1->name = "Wombaty"; echo $u2->name;

25.  The clone operator creates a new instance of the class and copies the attribute values from the original instance to the new instance.  Example: This prints “Wombat” $u1 = new User("Wombat", "womwom"); $u2 = clone $u1; $u1->name = "Wombaty"; echo $u2->name;

26.  Starting from PHP5, a method can be declared as static, which means that it is called on a class and not on an object  To call a static method, write the class’ name, followed by a double colon (::), followed by the method’s name

27.  Example: class User{ public $name; public $password; function User($param1, $param2){ $this->name=$param1; $this->password=$param2; } static function pwd_string(){ echo "Please enter your password"; } User::pwd_string();

28.  An attribute can be given a default value  It must be a constant and not the result of a function or expression  Example: class User{ public $name = "John Smith"; //valid public $password = time();//not valid }

29.  A constant is declared using const keyword. Its value, once declared, cannot be changed.  A constant’s name is usually written in all UPPERCASE letter.  Constants can be referenced directly, using the self keyword and the double colon operator (::)

30.  Example: Translate::lookup(); class Translate{ const ENGLISH = 0; const SPANISH = 1; const FRENCH = 2; const GERMAN = 3; //... static function lookup(){ echo self::SPANISH; }

31.  PHP 5 provides three keywords for controlling the scope of attributes and methods: public, protected, private.  The default scope is public

32.  public  can be referenced from anywhere  protected  can be referenced only by the object’s class methods and those of any subclasses.  private  can be referenced only by methods within the same class—not by subclasses.

33.  Once we have written a class, we can derive subclasses from it.  This is achieved using the extends operator. class Subscriber extends User{ public $phone, $email; function display(){ echo "Name: ". $this->name. " "; echo "Pass: ". $this->password. " "; echo "Phone: ". $this->phone. " "; echo "Email: ". $this->email; }

34.  The parent keyword is used to access the superclass’ attribute/methods  Example: accessing parent’s constructor class Subscriber extends User{ public $phone, $email; function Subscriber($p1, $p2, $p3, $p4){ parent::User($p1, $p2); $this->phone = $p3; $this->email = $p4; } When extending a class, PHP does not automatically calls the parent class’ constructor

35.  If you write a method in a subclass with the same name as one in its parent class, its statements will override those of the parent class.  However, the parent class’ method is still accessible by using parent keyword.

36.  In cases in which we wish to prevent a subclass from overriding a superclass’ method, we can use the final keyword.  Example: class User{ final function copyright(){ echo "This class was written by Joe Smith"; }