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<!-- Initial Contributors:+
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    Nokia Corporation - initial contribution.+
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Contributors: +
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<!DOCTYPE concept+
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  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">+
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<concept id="GUID-E161AB84-1B24-53AF-B313-D68CF9F8EE60" xml:lang="en"><title>Pointers+
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to the start and end of contiguous regions</title><shortdesc>The <codeph>Back()</codeph> and <codeph>End()</codeph> functions+
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point to locations in memory for flat and segmented arrays.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>+
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<p>For those arrays of same length elements which are derived from <codeph>CArrayFix&lt;class T&gt;</codeph>,+
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the elements are contained within an array buffer which can be implemented+
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as a flat buffer or as a segmented buffer. A flat buffer is implemented as+
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a single contiguous region of memory while a segmented buffer is implemented+
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as a set of separate but linked regions of memory </p>+
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<p>Given the position of an element within an array, it can be useful to fetch+
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a pointer to the first byte following the end of the contiguous region of+
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memory containing that element (the <i>end</i> pointer). Similarly, it can+
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be useful to fetch a pointer to the <i>beginning</i> of a contiguous region+
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of memory (the <i>back</i> pointer).</p>+
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<section id="GUID-DB6D5E2F-CFEE-47EC-B38D-9D0DC13B994D"><title>Array of same length elements</title> <p>An array of same+
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length elements uses the <codeph>End()</codeph> function to fetch the end+
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pointer and the <codeph>Back()</codeph> function to fetch the back pointer.+
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The implementation of these two functions differs between a fixed flat array+
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and a fixed segmented array.</p> </section>+
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<section id="GUID-48756A91-9B8F-4BA8-A0CF-52970F8B41CC"><title>Flat array</title> <p>For a flat array — i.e. an array whose+
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buffer is implemented using a flat buffer — the end pointer simply points+
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to the first byte following the single region of memory containing the array+
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buffer. The back pointer simply points to the first byte of the single region+
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of memory (as illustrated below); <codeph>End()</codeph> always returns a+
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pointer to the first byte following the end of the buffer, while <codeph>Back()</codeph> always+
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returns a pointer to the beginning of the buffer.</p> <fig id="GUID-D4084F4C-B928-5779-A58F-CB495A74EE68">+
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<title>End() and Back() in fixed flat arrays</title>+
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<image href="GUID-81A5784D-A0C6-5108-9E7B-5D39C6743B1A_d0e330021_href.png" placement="inline"/>+
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</fig> </section>+
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<section id="GUID-27F85346-3B08-4E06-A80D-A5B708105659"><title>Segmented array</title> <p>For a segmented array, the situation+
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is different (as illustrated below). Looking at the segment containing elements <codeph>n</codeph> and <codeph>n+1</codeph>, <codeph>End()</codeph> returns a pointer to the first byte following the end of that segment. In+
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fact, <codeph>End()</codeph> returns the same pointer value for all elements+
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in that segment. <codeph>Back()</codeph> returns a pointer to the beginning+
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of that segment for element <codeph>n+1</codeph> and for all <i>subsequent</i> elements+
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in that segment. However, for the <i>first</i> element in that segment, <codeph>Back()</codeph> returns+
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a pointer to the beginning of the <i>previous</i> segment. For the very first+
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element in the array, <codeph>Back()</codeph> returns a pointer with a NULL+
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value.</p> <fig id="GUID-90C05AF9-9048-557E-95DD-49A19F856EF0">+
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<title>End() and Back() in fixed segmented arrays</title>+
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<image href="GUID-C0CFFE13-579C-5A93-9B63-DC2DCF98EC61_d0e330070_href.png" placement="inline"/>+
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</fig> </section>+
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<section id="GUID-165D9F3E-3948-4DC0-9632-FF70480C495C"><title>See also</title> <p><xref href="GUID-112AAFA5-B4C9-5B62-A106-FB5097C13A0E.dita">Dynamic+
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Buffers Guide</xref>.</p> </section>+
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</conbody></concept>+
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