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<!DOCTYPE concept
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
<concept id="GUID-059326DB-E7A4-5CB8-BCA7-FF0C71D9D1C7" xml:lang="en"><title>How
to access elements</title><shortdesc>The elements of an array can be accessed by specifying the position
of the element in the array.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>The elements of an array can be referenced using the indexing  <codeph>operator[]</codeph> and
specifying the position of the element.</p>
<p>For all arrays <i>except</i> the <codeph>RArray&lt;class T&gt;</codeph> and <codeph>RPointerArray&lt;class T&gt;</codeph> types,
the <codeph>At()</codeph> member function can also be used.</p>
<p>All of the following code fragments use a <codeph>CArrayFixFlat&lt;class T&gt;</codeph> array.</p>
<p>This code constructs a fixed flat array containing the required number
of <codeph>TInt</codeph> type elements - in this case four.</p>
<p>The indexing operator is used to fetch the value of the second element.
This element is then changed, showing two different methods for changing the
element: the <codeph>At()</codeph> function and the <codeph>[]</codeph> operator.</p>
<codeblock id="GUID-44519EEA-85BA-54CF-9F4A-E67B043C8837" xml:space="preserve">CArrayFixFlat&lt;TInt&gt;* array;
array = new CArrayFixFlat&lt;TInt&gt;(4);
...
for (TInt value = 0; value &lt; 4; value++)
 array-&gt;AppendL(value);
...
TInt somevalue = (*array)[1];  //fetch the element
TInt somevalue = array-&gt;At(1);  //... alternative way
(*array)[1]    = 21;    //change the element
array-&gt;At(1)   = 21;    // ... alternative way</codeblock>
<section id="GUID-DD4808A9-0989-4A2E-B83C-B735BEDE0677"><title>Accessing functions</title> <p>If the array elements are objects
of a class with member functions, these functions can be easily accessed as
shown in the following code fragment:</p> <codeblock id="GUID-DD0C968E-B164-5EAA-9188-F0A323197652" xml:space="preserve">class TMyClass
 {
public :
 void SetValue(TInt aval);
 TInt GetValue();
private
 TUint iValue;
 };</codeblock> <codeblock id="GUID-39DDFF64-B1FC-5D93-8552-9D0FF4E5B6BD" xml:space="preserve">CArrayFixFlat&lt;TMyClass&gt;* array;          // an array of
                                         // TMyClass objects
TMyClass myclass;
array = new CArrayFixFlat&lt;TMyClass&gt;(1);
array-&gt;AppendL(myclass);
(*array)[0].SetValue(21);</codeblock> </section>
<section id="GUID-B2AE92D8-239C-4711-AA85-EEE9D333288C"><title>Accessing functions of CBase derived objects</title> <p>Where
the elements are pointers to <codeph>CBase</codeph> derived objects (i.e.
elements of an array of type <codeph>CArrayPtrFlat</codeph> or <codeph>CArrayPtrSeg</codeph>),
the members of those <codeph>CBase</codeph> derived objects can easily be
accessed. For example, an array of pointers to <codeph>CElement</codeph> objects
can be accessed as follows:</p> <codeblock id="GUID-D35D517A-0DB1-59A8-A6A3-BFDDF1C4610B" xml:space="preserve">CArrayPtrFlat&lt;CElement&gt;* ptrflat;
...
ptrflat = new (ELeave) CArrayPtrFlat&lt;CElement&gt;(16)
...
...   // add elements to ptrflat
...
(*ptrflat)[0]-&gt;SetTextL(_LIT("New text for the first CElement"));
ptrflat-&gt;At(1)-&gt;SetTextL(_LIT("New text for the second CElement"));</codeblock> <p>(where <codeph>SetTextL()</codeph> is
a member function of <codeph>Celement)</codeph>.</p> <p>Note that both <codeph>At()</codeph> and
the index <codeph>operator[]</codeph> return a reference to the object in
the array. </p> </section>
<section id="GUID-C8FB1FAE-F331-4B1D-9FEA-982A14986E42"><title>Refreshing the pointer</title> <p>If a pointer to the referenced
object is taken, be aware that the pointer value may become invalid once elements
are added to, or removed from the array. In this event, always refresh the
pointer. </p> <codeblock id="GUID-FE89CB4A-821E-515D-B963-58D4C288E385" xml:space="preserve">class TMyClass
 {
public :
 void SetValue(TInt aval);
 TInt GetValue();
private
 TUint iValue;
 };</codeblock> <codeblock id="GUID-D727EFF4-DA87-54F8-8E4C-761F11E5726A" xml:space="preserve">CArrayFixFlat&lt;TMyClass&gt;* array;
...
TMyClass myclass;
array = new CArrayFixFlat&lt;TMyClass&gt;(16);
...
for (TInt val = 0; val &lt; 10; val++)
 {
 myclass.SetValue(val)
 array-&gt;AppendL(myclass;
 }
...
TMyClass* myptr;
myptr = &amp;(array-&gt;At(9));
myptr-&gt;GetValue();  // references the tenth element
array-&gt;Delete(0,4); // Delete first four elements
array-&gt;Compress();  
myptr-&gt;GetValue();  // myptr is invalid. An exception may occur
...</codeblock> <p>After deleting the first four elements, <codeph>myptr</codeph> points
to a location outside the logical array. Once the array has been compressed,
the pointer is invalid. </p> </section>
</conbody></concept>