Earlier state plus declaration <CODE>float *Q;</CODE>
<PRE>        <IMG SRC="Lecture2dFig9.gif"></PRE>
<CODE>Q = P;</CODE> copies into <CODE>Q</CODE> the value stored in
<CODE>P</CODE>
<PRE>        <IMG SRC="Lecture2dFig10.gif"></PRE>
<CODE>*P</CODE> and <CODE>*Q</CODE> are now two names for the same
location. We can change the value stored at that location using one
name, e.g. <CODE>*P = 2.5;</CODE>
<PRE>        <IMG SRC="Lecture2dFig11.gif"></PRE>
Now <CODE>*Q</CODE> is also 2.5. <CODE>P == Q</CODE> tests for pointer
equality, i.e. do they contain the same address. In the above diagram
<CODE>P == Q</CODE> is true.
<PRE>        <IMG SRC="Lecture2dFig12.gif"></PRE>
In this one however <CODE>P == Q</CODE> is false, but
<CODE>*P == *Q</CODE> is true.