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<concept id="GUID-02E674F7-86F1-5A9C-8189-F4CEE80D9FBD" xml:lang="en"><title>How

to remove elements</title><shortdesc>It is possible to remove one or several contiguous elements from

any array. Deleting elements from an array may not automatically free up memory.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>Elements can be removed from an array.</p>

<p>The following code fragment shows the deletion of the second <codeph>TElement</codeph> object

from a <codeph>CArrayFixFlat&lt;class T&gt;</codeph> array:</p>

<codeblock id="GUID-B76A9F01-85DA-5BE3-A89E-67AEA5011A5F" xml:space="preserve">class TElement

 {

public :

 TElement();

public :

 TBuf<4> iData;

 };</codeblock>

<codeblock id="GUID-97D12B24-E03C-549F-975D-E2DD72A11A81" xml:space="preserve">CArrayFixFlat&lt;TElement&gt;* fixflat;

fixflat = new (ELeave) CArrayFixFlat<TElement>(3);

...

...        // elements added to the array at some point

...

fixflat-&gt;Delete(1);</codeblock>

<p>To delete what are now the third and fourth elements from the array, i.e.

the two contiguous elements starting at position two, use <codeph>Delete()</codeph> and

specify both the starting position and the number of elements:</p>

<codeblock id="GUID-041A95DA-A332-5CBE-8D28-D0257DCC5255" xml:space="preserve">fixflat-&gt;Delete(2,2);</codeblock>

<section id="GUID-B9040865-C163-4A0B-B509-DAFA8BC39CE2"><title>Notes</title> <ul>

<li id="GUID-AFA7DA8D-26A5-5FCA-A4F8-25627D209CE8"><p>Deleting elements from

an array does not automatically compress the array buffer; the space allocated

to the array buffer remains unchanged. This means that adding an element to

a <i>same length</i> type array <i>after</i> deleting an element is <i>guaranteed</i> not

to fail. However, this is <i>not</i> true for a variable length array and

is only true for a packed array if the size of the new element is less than

or equal to the size of the deleted element.</p> </li>

<li id="GUID-3DE5FD87-8557-586C-84E7-7F2105483296"><p>Excess space in the

array buffer can be removed using the <codeph>Compress()</codeph> member function.

This reduces the capacity of the array. For a same length flat array, an attempt

to add an element after compression causes re-allocation of the flat buffer.

To compress the array:</p> </li>

</ul> <codeblock id="GUID-A9C18AD8-1D3B-5F2A-80A6-FD06846C1D0C" xml:space="preserve">fixflat-&gt;Compress();</codeblock> <ul>

<li id="GUID-7595C77D-73A7-539C-B18B-2E1DE51EF4BA"><p>All elements within

an array can be deleted using the <codeph>Reset()</codeph> function. This

function also compresses the array. Compressing the array when it is empty

causes the memory allocated to the array buffer to be freed.</p> </li>

<li id="GUID-00AADD5C-E4E0-5C68-B1D3-4906973A6299"><p>For an array of pointers

to <codeph>CBase</codeph> derived objects (i.e. a <codeph>CArrayPtrFlat</codeph> or

a <codeph>CArrayPtrSeg</codeph> type array), some care should be taken when

deleting elements from the array. The following code fragment deletes the

last two elements from <codeph>ptrflat</codeph> (a <codeph>CArrayPtrFlat</codeph> array)

and deletes the objects that those elements point to:</p> </li>

</ul> <codeblock id="GUID-B853D5EE-11A0-50C7-9CC6-6705A5118AC3" xml:space="preserve">TInt      index;

CElement* ptr;

...

index = ptrflat->Count();

...

ptr = (*ptrflat)[--index];

ptrflat->Delete(index);

delete ptr;

...

ptr = ptrflat->At(--index);

ptrflat->Delete(index);

delete ptr;</codeblock> <ul>

<li id="GUID-0C733A40-7B7D-518B-B27F-5E25DB73435A"><p>In general, before the

elements of this kind of array are deleted, the <codeph>CBase</codeph> derived

objects to which those elements point should be destroyed. If they are not

destroyed, then a separate copy of those elements (i.e. the pointers), <i>must</i> be

taken to avoid orphaning the <codeph>CBase</codeph> derived objects on the

heap.</p> </li>

</ul> </section>