<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE task

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

<task id="GUID-EA107811-240C-5F95-922B-7C042FA00A87" xml:lang="en"><title>Reading

a String Resource </title><abstract><p>The simplest use of a resource file involves reading string resources

and interpreting the source data. </p></abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context><p>Resources are defined in terms of structs which are accessed and

read by the <xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita"><apiname>RResourceFile</apiname></xref> class, and interpreted by the <xref href="GUID-B375D32E-1F91-30FA-8605-A2E163111F9A.dita"><apiname>TResourceReader</apiname></xref>.

An application may also use resources from multiple files simultaneously.

See <xref href="GUID-98903A01-CD04-5345-84AE-2E440CE06E11.dita">Resource File examples</xref> for

more information. </p><p>Consider a sample resource file where a struct of

STRING is defined having a single member of type <codeph>LTEXT</codeph>: </p><codeblock xml:space="preserve">// define structures

STRUCT STRING

    {

    LTEXT text;

    }

// define resources

RESOURCE STRING hello

    {

    text=Bonjour tout le monde!;

    }

</codeblock> </context>

<steps id="GUID-F147E8CF-65D1-5025-BA85-E0D171DBEFFD">

<step id="GUID-0BAEB54B-5A6E-59F6-B14E-FAF0A3D15F27"><cmd/>

<info>Compile the resource file using <xref href="GUID-9C57F0C6-E2E3-58A2-907D-924A7E22EA97-GENID-1-11-1-1-5-1-4-1.dita">the

resource compiler</xref> (rcomp) to generate an <filepath>.rsc</filepath> file

and an <filepath>.rsg</filepath> file. </info>

<substeps id="GUID-0B421705-A5CD-5FF7-BB95-C17559811267">

<substep id="GUID-673E32C9-665C-5388-AE17-780A149F8837"><cmd/>

<info> <filepath>.rsc</filepath> file contains the resource data; this is

the resource file that must be referred to at run-time by the <codeph>RResourceFile</codeph> class

in the C++ code. </info>

</substep>

<substep id="GUID-AEE254EB-0716-5478-B1DF-F8ED8E4FF8E1"><cmd/>

<info> <filepath>.rsg</filepath> file is a <keyword>generated            

         header</keyword> file that contains <codeph>#define</codeph> statements

for each resource defined in the source file. In the resource file generated

here, the only resource is called <codeph>hello</codeph> and the generated

header file contains: </info>

<stepxmp><codeblock id="GUID-385BB8E3-FF77-5A95-8F65-043E72412959" xml:space="preserve">#define HELLO 1</codeblock> </stepxmp>

<info>Note that the name in the generated header file is converted to upper

case. </info>

</substep>

</substeps>

</step>

<step id="GUID-3367B1DD-C2E9-5780-A77A-7F574D2EC541"><cmd/>

<info> <codeph>#include</codeph> the <filepath>.rsg</filepath> file in the

file containing the C++ code, to access the resource IDs generated by the

resource compiler. For example, for a project refered as <codeph>ReadText</codeph>,

this might be: </info>

<stepxmp><codeblock id="GUID-AC615F67-6331-500C-B91E-ADD6A94464FB" xml:space="preserve">#include ReadText.rsg</codeblock> </stepxmp>

</step>

<step id="GUID-ACC66DA2-4AC8-536B-9912-7CE632C0A8DF"><cmd/>

<info>Initialize the <codeph>RResourceFile</codeph> object in the C++ program,

specifying the name of the resource file: </info>

<stepxmp><codeblock id="GUID-5CF79231-E42C-51DF-9002-FD1ED8AB21C1" xml:space="preserve">    

RResourceFile resourceFile;

resourceFile.OpenL( fsSession,_L( Z:\\system\\data\\ReadText.rsc ) );</codeblock> </stepxmp>

<info>Note: To access the resource file contents, a session with the file

server must be started using an instance of <xref href="GUID-E263C747-946F-35AA-9F1D-41833BD350FC.dita"><apiname>RFs</apiname></xref> class. </info>

</step>

<step id="GUID-CA53A8D1-E13E-50A8-96A7-B6B397B82DB3"><cmd/>

<info>Use one of the three functions (<xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita#GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA/GUID-9B16E6B8-84A4-37DF-BBB4-EC8B04FDB14C"><apiname>RResourceFile::AllocReadLC()</apiname></xref>, <xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita#GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA/GUID-8CEE29E0-78F3-3DD6-B068-85C8E0403884"><apiname>RResourceFile::AllocReadL()</apiname></xref> or <xref href="GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA.dita#GUID-AA6DEF11-6F23-3523-A9F7-F15DF918E1BA/GUID-DF6DFFD5-E923-3C4E-87F0-BC4EE7C8B586"><apiname>RResourceFile::ReadL()</apiname></xref> to read a resource as shown in the following

code fragment: </info>

<stepxmp><codeblock id="GUID-92AC4270-4A4D-52F1-B5C4-CFF6FBD19700" xml:space="preserve">HBufC8* dataBuffer = resourceFile.AllocReadLC( HELLO );</codeblock> </stepxmp>

</step>

<step id="GUID-77F9A976-6E09-5158-B515-256F4B878CDB"><cmd/>

<info>Interpret the resource data using a <codeph>TResourceReader</codeph> object.

This provides access to the text string through a pointer descriptor as shown

in the following code fragment: </info>

<stepxmp><codeblock id="GUID-CB3BE44D-72F5-5E15-8D1D-52F513D9D980" xml:space="preserve">

TResourceReader theReader;

...

theReader.SetBuffer( datafBuffer );

TPtrC textdata = reader.ReadTPtrC();</codeblock> </stepxmp>

</step>

</steps>

<result><p>In this example, once the resource data is no longer needed, the

heap descriptor, dataBuffer, can be removed from the cleanup stack and destroyed

as shown in the code fragment: </p><codeblock xml:space="preserve">CleanupStack::PopAndDestroy();</codeblock><p>When

all operations on the resource file are complete, the resource file can be

closed using the RResourceFile::close() function as:  </p><codeblock xml:space="preserve">resourceFile.Close();</codeblock></result>

<example><title>Example</title> <p>Consider a resource constructed

from the following definition. </p> <codeblock id="GUID-538D959C-A85A-5675-9B14-ED81AB860F47" xml:space="preserve">RESOURCE ARRAY anarray

{

items=

    {

    LBUF { txt="Esc"; },

    LBUF { txt="Enter"; },

    LBUF { txt="Tab"; },

    LBUF { txt="Del"; },

    LBUF { txt="Space"; }

    };

}</codeblock> <p>A <codeph>TPtrC</codeph> representing the second item can

be constructed using the <codeph>ReadTPtrC()</codeph> function. The example

simply takes the length of the text <codeph>Enter</codeph>: </p> <codeblock id="GUID-9817910D-0661-513D-BB3A-9557D70688AD" xml:space="preserve">// open the resource file

...

HBufC8* res = resourceFile.AllocReadLC( ANARRAY );

TResourceReader theReader;

...

TInt len;

len = ( theReader.ReadTPtrC( 1,res ) ).Length(); // len == 5

...</codeblock> </example>

</taskbody><related-links>

<link href="GUID-3AF1F492-3D7D-5F8C-B1AE-16FBD8224775.dita"><linktext>Resource

files</linktext></link>

<link href="GUID-07C031C2-7FFC-5B0E-9691-E6E678E65C4B.dita"><linktext>Resource

file format</linktext></link>

<link href="GUID-3527AAEE-210F-524B-A655-A65F1CE86C80.dita"><linktext>Resource

compilation</linktext></link>

</related-links></task>