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<!DOCTYPE task

  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

<task id="GUID-548CC331-8E38-5627-A925-EA386BE90258" xml:lang="en"><title>Compressing

and Decompressing File - GZip Format </title><abstract><shortdesc>The Zip Compression Library, EZLib provides file compression

and decompression functionality for the Symbian platforms. The files can be

compressed to two formats namely zip and gzip. gzip is normally used to compress

single files. </shortdesc> <p/> </abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context id="GUID-48E514AC-C78B-570F-A96C-389BABA02472"><p>Compression and

Decompression are performed iteratively, till the completion of required task. </p> </context>

<steps id="GUID-2D2DC7F3-64FA-5C96-95DE-615650E10160">

<step id="GUID-C384EAE0-B1EE-5098-A557-1231D35F8A2A"><cmd/>

<info>Input the source file and the name of the target gzip file to an instance

of the <xref href="GUID-417AB4E0-FF07-34CB-A4A8-CEF31C48A162.dita"><apiname>CEZFileToGZip</apiname></xref> class. </info>

</step>

<step id="GUID-2A30A687-A777-5790-8145-5AE956F35FFC"><cmd/>

<info> <xref href="GUID-417AB4E0-FF07-34CB-A4A8-CEF31C48A162.dita#GUID-417AB4E0-FF07-34CB-A4A8-CEF31C48A162/GUID-4E51D7C5-C624-3F27-A5CD-01E92F96F72B"><apiname>CEZFileToGZip::DeflateL()</apiname></xref> is used to compress the

file. </info>

</step>

</steps>

<example><p>The code below depicts how the source file "input.doc" file is

converted to target file "output.gz". </p><codeblock xml:space="preserve">/*

 * If input and output file names are not specified then it is assumed that 

 * the file names are contained in a provided .ini file.

 */

void CEZlibEZipTests::DoEZlibGZipDeflateL()

    {

 RFs iFs;

 iFS.connect();

    //Open the source file in read mode

_LIT(KInputFileLocation, "c:\\private\\E80000B7\\zip\\input\\input.doc");

TFileName inputFile(KInputFileLocation);

    RFile input;

    err = input.Open(iFS, inputFile, EFileStream | EFileRead | EFileShareExclusive);

    if(err != KErrNone)

        {

        INFO_PRINTF1(KOpenFileError);

        User::Leave(err);

        }   

    //create a target file

_LIT(KOutputFileLocation, "c:\\private\\E80000B7\\zip\\input\\output.gz");

TFileName outputFile(KOutputFileLocation);

    CEZFileToGZip *compressor = CEZFileToGZip::NewLC(iFs, outputFile, input);

    while(compressor->DeflateL())

        {       

        }   

input.Close();

    iFS.Close();

    }

</codeblock></example>

<postreq><p>The decompression of a gzip file can be achieved through the following

the steps: </p> <ol id="GUID-A4771CC4-2704-56E3-BBD5-4AB2A58F9468">

<li id="GUID-4E130CBF-C626-5CD0-9A83-A2F138B12B68"><p>Pass the file to the

constructor of the <xref href="GUID-8DE05785-D058-3855-A11F-7132EB4DE078.dita"><apiname>CEZGZipToFile</apiname></xref> class. </p> </li>

<li id="GUID-CB642B02-8A19-5CB9-96E4-80AB7596F6E1"><p> <xref href="GUID-8DE05785-D058-3855-A11F-7132EB4DE078.dita#GUID-8DE05785-D058-3855-A11F-7132EB4DE078/GUID-4A30D99E-EC51-359F-90B5-9CFA3841A538"><apiname>CEZGZipToFile::InflateL()</apiname></xref> is

called repeatedly to complete the decompression. </p> </li>

</ol> <p>The code below depicts how "output.gz" is decompressed to "input.doc". </p> <codeblock id="GUID-01545D8D-CE1F-5903-9558-CE35D4C3067E" xml:space="preserve">/*

 *  If  input and output file names are not specified then it is assumed that 

 * the file names are contained in a provided .ini file.

 */

void CEZlibEZipTests::DoEZlibGZipInflateL()

    {

      RFs iFs;

  iFS.connect();

    //open output file

_LIT(KOutputFile, "c:\\private\\E80000B7\\zip\\input\\input.doc");

TFileName outputFile(KOutputFile);

    RFile output;

    err = output.Replace(iFs, outputFile, EFileStream | EFileWrite | EFileShareExclusive);

    if(err != KErrNone)

        {

        INFO_PRINTF1(KCreateFileError);

        User::Leave(err);

        }    

//input file

_LIT(KInputFileLocation, "c:\\private\\E80000B7\\zip\\input\\output.gz");

TFileName inputFile(KInputFileLocation);

    CEZGZipToFile *decompressor = CEZGZipToFile::NewLC(iFs, inputFile, output);

        while(decompressor->InflateL())

        {        

        }    

        output.Close();

    iFS.Close();

    ;

    }</codeblock> </postreq>