<concept id="GUID-4CC4D912-810B-4542-AFCD-58CEE8E0128C" xml:lang="en"><title>Open C libz Example</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>The example demonstrates how to use the libz library to compress

a file and decompress it. The library can compress and decompress

any kind of file (txt, doc, xls, xml, mpeg, ppt, mp3 etc). </p>

<section id="GUID-026FD8D6-6C4A-5958-B289-775D4AE1E756-GENID-1-10-1-13-1-1-5-1-3-1-11-1-11-1-2-2"><title>Download</title> <p>Click on the following link to download the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-4e9f70e8-96f8-45be-90fc-00c9071cf562.zip" scope="external"> openclibz.zip</xref></p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-4e9f70e8-96f8-45be-90fc-00c9071cf562.html" scope="peer">browse</xref> to view the example code. </p> </section>

<section id="GUID-7E7C4564-B10E-41F9-8A9D-D8A6C5E9C51C-GENID-1-10-1-13-1-1-5-1-3-1-11-1-11-1-2-3"><title>Design

and Implementation</title> <p>The following sections provide more

information about the steps that the example performs. </p> <p><b>Capabilities</b> </p>Program capabilities are defined in <filepath>openclibz.mmp</filepath>: <codeph>CAPABILITY None</codeph><p><b>Implementation

details of EXE</b> </p>This example is a console based application.

This application can be launched from the icon (openclibz) in installed

folder and also from eshell.  When we launch it through icon it prompts

the user to enter the mode to process. The strategy parameter is used

to select the compression algorithm. For compressing a file, it reads

the file and then compresses it using the API of the libz library

and then stores the compressed content in a (.gz) file. If you want

to decompress, type d.  For decompressing a file, it opens the compressed

(.gz) file using libz API's  and then reads the content and decompresses

it . To check what happens to the content of the string after compression

then type s. Enter the string you want and see the data in compressed

format .   This option is to demonstrate compression of string using

libz API's.<p>To run this application through eshell: </p><p><codeblock xml:space="preserve"> Usage :  openclibz [-d] [-f] [-h] [-r] [-1 to -9] [files...]

process, enter the file name. You should provide absolute path of

the file you want to compress.  <filepath>(drive letter):\[(folder

name)\]filename</filepath>.   To get : on phone you have to press

1 few times.  To get on phone you have to press 1 few times.  To get

on emulator is bit tricky. If you are lucky then pressing 1 will get

it for you, otherwise change the mode. using "\ BUTTON" (Just above

the enter button in the keyboard) and then try pressing 1.  To press

enter on phone we are supposed to press 0 four times. </p><p><b>Cross

platform usage</b></p><p>We can compress the file on any platform

and uncompress it on any other platform.  For example Unix's gzip

files can be compressed using the example application and decompressed

using Unix's gunzip.   Compression can be done in a single step, if

the buffers are large enough; or compression can be done by repeated

calls of the compression function. In the second scenario, application

must provide more input and consume the output (providing more output

space) before each call. </p></section>

<section id="GUID-D72E3F44-9925-456B-9B1D-FBCBAC2548DA"><b>APIs Used</b><p><codeph>compress</codeph>, <codeph>uncompress</codeph>, <codeph>gzopen</codeph>, <codeph>gzclose</codeph>, <codeph>gzread</codeph>, <codeph>gzwrite</codeph>, <codeph>gzerror</codeph> from libz library</p><p> <codeph>fopen</codeph>, <codeph>fclose</codeph>, <codeph>fread</codeph>, <codeph>fwrite</codeph>, <codeph>mmap</codeph>, <codeph>munmap</codeph>, <codeph>fstat</codeph>, <codeph>unlink</codeph>, <codeph>printf</codeph>, <codeph>scanf</codeph> from libc library </p></section>

<section id="GUID-67A72761-1D92-46D1-B1C9-7455978BDE4E-GENID-1-10-1-13-1-1-5-1-3-1-11-1-11-1-2-5"><title>Building

and Using</title> <p>The Symbian build process describes how to build

this example application. </p> To build the example

application, go to the openclibz\group directory and build the application.

 The definition for the whole application can be found in the bld.inf

file in the group subdirectory of the applications main directory. </section>