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<b>Data Structures and Algorithms 
with Object-Oriented Design Patterns in C++</b><br>
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<H2><A NAME="SECTION005170000000000000000">Resizing an Array</A></H2>
<A NAME="secfdsresize">&#160;</A>
<P>
The definitions the <tt>SetBase</tt> and <tt>SetLength</tt> member functions
of the <tt>Array&lt;T&gt;</tt> class are given in Program&nbsp;<A HREF="page87.html#progarray7c" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/page87.html#progarray7c"><IMG  ALIGN=BOTTOM ALT="gif" SRC="cross_ref_motif.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/icons/cross_ref_motif.gif"></A>.
The <tt>SetBase</tt> function simply modifies the <tt>base</tt> field as required.
The <tt>SetLength</tt> function provides a means
to change the size of an array at run time.
This function can be used both to increase and to decrease
the size of an array.
<P>
<P><A NAME="2884">&#160;</A><A NAME="progarray7c">&#160;</A> <IMG WIDTH=575 HEIGHT=313 ALIGN=BOTTOM ALT="program2812" SRC="img607.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img607.gif"  ><BR>
<STRONG>Program:</STRONG> <tt>Array&lt;T&gt;</tt> Class <tt>SetBase</tt> and <tt>SetLength</tt>      Member Function Definitions<BR>
<P>
<P>
The running time of this algorithm depends on two parameters.
If <I>n</I> is the original size of the array
and <I>m</I> is the new size of the array,
then the running time of <tt>Resize</tt> is
 <IMG WIDTH=478 HEIGHT=26 ALIGN=MIDDLE ALT="tex2html_wrap_inline60993" SRC="img608.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img608.gif"  >.
This is because the program first allocates and initializes
a new array of size <I>m</I>;
then it copies at most  <IMG WIDTH=69 HEIGHT=24 ALIGN=MIDDLE ALT="tex2html_wrap_inline60997" SRC="img609.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img609.gif"  > elements from the old array
to the new array;
and then it deletes the old array.
And in the case where <tt>T</tt> is a built-in C++ data type,
this simplifies to  <IMG WIDTH=288 HEIGHT=26 ALIGN=MIDDLE ALT="tex2html_wrap_inline60999" SRC="img610.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img610.gif"  >.
<P>
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