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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="SECTION005290000000000000000">Copy Constructor and Assignment Operator</A></H2>
<P>
The code for the copy constructor and assignment operator (<tt>operator=</tt>)
of the <tt>LinkedList<T></tt> class is given in Program <A HREF="page97.html#proglinklist7c" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/page97.html#proglinklist7c"><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>.
These functions are similar in that they both build a copy of a given list.
The copy constructor first initializes
the member variables to represent the empty list.
Then, it traverses the referenced list one-by-one,
calling the <tt>Append</tt> function to append the items
of the referenced list to the list begin constructed.
<P>
<P><A NAME="3843"> </A><A NAME="proglinklist7c"> </A> <IMG WIDTH=575 HEIGHT=447 ALIGN=BOTTOM ALT="program3683" SRC="img628.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img628.gif" ><BR>
<STRONG>Program:</STRONG> <tt>LinkedList<T></tt> Class Copy Constructor Definition<BR>
<P>
<P>
In Section <A HREF="page96.html#secfdsappend" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/page96.html#secfdsappend"><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 running time for the <tt>Append</tt>
function was determined to be <IMG WIDTH=124 HEIGHT=26 ALIGN=MIDDLE ALT="tex2html_wrap_inline61025" SRC="img621.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img621.gif" >.
If the resulting list has <I>n</I> elements,
the <tt>Append</tt> function will be called <I>n</I> times.
Therefore, the running time of the copy constructor is <IMG WIDTH=190 HEIGHT=26 ALIGN=MIDDLE ALT="tex2html_wrap_inline61053" SRC="img629.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img629.gif" >.
If <tt>T</tt> is one of the built-in types, <IMG WIDTH=126 HEIGHT=26 ALIGN=MIDDLE ALT="tex2html_wrap_inline60973" SRC="img601.gif" tppabs="http://dictator.uwaterloo.ca/Bruno.Preiss/books/opus4/html/img601.gif" >.
As a result, the running time of the copy constructor would be <I>T</I>(<I>n</I>)=<I>O</I>(<I>n</I>).
<P>
The assignment operator first calls <tt>Purge</tt> to make sure
that the list to which new contents are being assigned is empty.
It then builds a copy of the given list
in the same way as discussed above for the copy constructor.
The running time is equal to that of the <tt>Purge</tt> function
plus that of the copy constructor.
<P>
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