Indeed <CODE>P</CODE> and <CODE>Q</CODE> point to distinct locations
that happen to contain identical values:
<PRE>        <IMG SRC="Lecture2dFig12.gif"></PRE>
If we change one of them, the other is unaffected, e.g.
<CODE>*Q = 3.7;</CODE>
<PRE>        <IMG SRC="Lecture2dFig13.gif"></PRE>
To test if 2 locations contain the same value, we must compare their
contents rather than their addresses: <CODE>*P == *Q</CODE>.

<P>Remember the difference between <CODE>P</CODE> and <CODE>*P</CODE>.
If we do <CODE>P = Q</CODE>, we get:
<PRE>        <IMG SRC="Lecture2dFig14.gif"></PRE>
but <CODE>*P = *Q</CODE> yields:
<PRE>        <IMG SRC="Lecture2dFig15.gif"></PRE>