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PclZip User Guide - Understanding how it works

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Understanding how it works

Internal representation of a PKZIP archive

Each PKZIP archive is represented by an object of class PclZip. When creating a PclZip archive (on object of class PclZip), the name of the archive file is associated to the object. At this time the file is not checked, nor read, it can even don't exist at this time.

$archive = new PclZip("");

The archive is then manipulated by using the public methods associated with PclZip object. To create an archive, when it does not already exist, the method ' create()' must be used, with a list of files and/or folders to archive as parameter.
If the archive already exist, its content can be read by access methods like ' listContent()' or ' extract()'.

Parameters and arguments

Each method has its own arguments which are described in the synopsis ofthe method. These arguments can be mandatory or optional. Example :

$archive = new PclZip('');
$v_list = $archive->add('dev/file.txt',

Here the first parameter 'dev/file.txt' is mandatory, while 'PCLZIP_OPT_REMOVE_PATH, ...' is optional.

Some methods can also be called only with a variable list of optional arguments :

   $list  =  $archive->extract(PCLZIP_OPT_PATH, "folder",
PCLZIP_CB_PRE_EXTRACT, "callback_pre_extract",
PCLZIP_CB_POST_EXTRACT, "callback_post_extract");

Here the files are extracted in 'folder', and the 'data' path, when present in the archive, is removed.
Also, before each extraction of a single file from the archive, a callback function, which name is provided by the user (here 'callback_pre_extract()'), is called. This function gives the ability to change the path and the filename that is in the extraction process, or to skip the extraction of this particular file.
At the end of the extraction of the file an other call-back function is called, giving the ability to the user to perform specific actions on the file before extracting the next one.

 $list = $archive->extract(PCLZIP_OPT_PATH, "folder" ,

Here the files are extracted in the directory 'folder' and all the memorized path of the files are removed, even if they are different. By this feature the user does not have to specify the exact value of a path to remove.

These small examples shows how the variable list of options works. They offer better features (with the cost of a little more complexity). They will also ease the introduction of new features without changing the synopsis of all the methods.

The defined arguments, their usage and restrictions are described in the section " Optional Variable Parameters". In the description of each method, the list of available optional parameters are indicated.

Return values

Return values may be different from methods to methods. They are described in each method synopsis.
However most of the methods returns 0 on error (and set the error flag), or an array describing each file on success.
Each entry of this array describe a file or folder, some of its properties and the specific status of the last action on the file.

Each file is described by the following arguments :


Name of the file.
For an add, it is the name given when calling the method.
For extraction it is the real name of the extracted file (not the name stored in the archive).


Stored name of the file.


Real size of the file


Compressed size in the archive (without header overhead)


Last modification date and time of the file (UNIX timestamp)


Comments associated with the file.


true | false : Indicates if the name if the name of a file or a folder.


Index of the file in the archive (when set).


Content of the extracted file. This row is present only when the option argument PCLZIP_OPT_EXTRACT_IN_STRING is set.


Result of the action (depend on the action type).
Values are :


OK !


the file/folder was not extracted (filtered by the user).


the file was not extracted because a folder with same name already exists.


the file was not extracted because a file with same name already exists and is write protected.


the file was not extracted because a more recent file exists.


the file was not extracted because an error occurs while creating its path.


the file was not extracted because a write error occur


the file was not extracted because a read error occur


the file was not extracted because of a bad header


the file was not extracted or added because a user call-back function request to skip it.
(Introduced in version 1.3)


the file was not added in the archive because the filename is too long (maximum 255 caracters).
(Introduced in version 1.3)


Introduction [Table Of Content] Optional Arguments


Last Updated on Friday, 18 December 2009 14:02