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<task id="GUID-3D50D2DE-A202-5560-80AB-0DBAC332179F" xml:lang="en"><title>Querying

a Feature Set Dynamically Using CFeatureDiscovery</title><shortdesc>How to query a feature set using <codeph>CFeatureDiscovery</codeph> dynamically. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>

<context id="GUID-2D805B5A-E4F5-5677-8114-AA8E5F17A221"><p>To query whether

a feature is supported in a feature set using <xref href="GUID-2C9E6E72-2858-37A1-9D43-4E8086569520.dita"><apiname>CFeatureDiscovery</apiname></xref> dynamically,

take the following steps. </p> </context>

<steps id="GUID-88C90174-AA62-55B4-B2A7-FDC8B833081F">

<step id="GUID-889198A4-C9A7-56C2-8F92-A334C7569C57"><cmd/>

<info>Decide the set of features you want to query and determine their Uids, </info>

</step>

<step id="GUID-52AF6109-A249-5F38-9634-01BD72486DA6"><cmd/>

<info>create an instance of <xref href="GUID-7C19450F-41CF-3293-B8BF-4A4D6F795155.dita"><apiname>TFeatureSet</apiname></xref>, </info>

<stepxmp><codeblock id="GUID-A4291810-0E7B-56BD-843F-6EF46DC523CE" xml:space="preserve">

  // Dynamic way of using multiple feature query. This is preferred

  // way to fetch support statuses if there are several features to be 

  // queried, because it involves less inter-process communication.

  TFeatureSet featset;

</codeblock> </stepxmp>

</step>

<step id="GUID-B3F1CECE-D775-5543-BA94-B4AAD2D5246D"><cmd/>

<info>add each feature you want to query by calling the <xref href="GUID-15C03838-4E72-3459-AE9E-52359DC065FD.dita"><apiname>Append()</apiname></xref> function

of <xref href="GUID-7C19450F-41CF-3293-B8BF-4A4D6F795155.dita"><apiname>TFeatureSet</apiname></xref> with the Uid of the feature as argument

(one call for each feature), </info>

<stepxmp><codeblock id="GUID-71DE607E-3204-5CA5-846B-998155071135" xml:space="preserve">

  User::LeaveIfError( featset.Append( <featureUIDx> ) );

  User::LeaveIfError( featset.Append( <featureUIDx> ) );

</codeblock> </stepxmp>

</step>

<step id="GUID-4F96DE36-2FA4-5465-8DDF-2EC53F468950"><cmd/>

<info>create an instance of <xref href="GUID-2C9E6E72-2858-37A1-9D43-4E8086569520.dita"><apiname>CFeatureDiscovery</apiname></xref>, </info>

<stepxmp><codeblock id="GUID-F4DFBFD2-AF1E-5E0B-BE83-E2233268D364" xml:space="preserve">

  // Call NewLC() to create an instance of CFeatureDiscovery.

  // The method leaves the instance of the object on the cleanup stack.

  CFeatureDiscovery* testB = CFeatureDiscovery::NewLC();

</codeblock> </stepxmp>

</step>

<step id="GUID-28A2A4F9-B510-5CE2-A3FC-FC7CC29D9242"><cmd/>

<info>call its <xref href="GUID-EA75A8A3-9862-3AAE-AC00-FCBEBA42BE34.dita"><apiname>FeaturesSupported()</apiname></xref> function with the <xref href="GUID-7C19450F-41CF-3293-B8BF-4A4D6F795155.dita"><apiname>TFeatureSet</apiname></xref> as

argument, and </info>

<stepxmp><codeblock id="GUID-516EA63D-42E3-5E6D-AD68-DD4A7E0EDE85" xml:space="preserve">

  // Call the exported IsSupported() method to query whether features 

  // are supported in the current environment or not. 

  TBool wcdmaSupported = testB->IsSupported(<featureUIDx>);

  TBool gsmSupported = testB->IsSupported(<featureUIDx>);

</codeblock> </stepxmp>

</step>

<step id="GUID-CC3CEDB9-7289-516E-968F-B04760CA6DA4"><cmd/>

<info>destroy the <xref href="GUID-2C9E6E72-2858-37A1-9D43-4E8086569520.dita"><apiname>CFeatureDiscovery</apiname></xref> instance when you have

finished with it if it was created with <xref href="GUID-93132FF9-512F-30EC-8AB0-BD3E98F668E6.dita"><apiname>NewL()</apiname></xref> rather than <xref href="GUID-343E6447-4947-34EE-8641-3CB72930CCF6.dita"><apiname>NewLC()</apiname></xref>. </info>

</step>

</steps>

</taskbody><related-links>

<link href="GUID-711594BD-9B8E-5E8A-A5A9-6C94F65AF064.dita"><linktext>Querying

a single feature                 dynamically using CFeatureDiscovery</linktext>

</link>

<link href="GUID-08ED8657-DB96-59AC-9016-602BD5680752.dita"><linktext>Querying

a single feature                 statically using CFeatureDiscovery</linktext>

</link>

<link href="GUID-DAC496E8-C8D0-5EC6-9A5D-5F5DA667D083.dita"><linktext>Querying

a feature set statically                 using CFeatureDiscovery</linktext>

</link>

<link href="GUID-B7A7E2E8-E727-5A01-8C1B-60679B6AA3D4.dita"><linktext>Querying

a Single Feature                 Dynamically Using RFeatureControl</linktext>

</link>

<link href="GUID-B71AC5E3-8AA8-55AD-916F-9E873926011B.dita"><linktext>Feature Manager

Collection Overview</linktext></link>

<link href="GUID-1A22E574-831B-5D00-98BD-0DFFA9CC09A0.dita"><linktext>Feature Manager

Query Tutorials</linktext></link>

</related-links></task>