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<title>2.3.2 Boolean Operations -- and, or, not </title>
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<H2><A NAME="SECTION004320000000000000000"></A><A NAME="boolean"></A>
<BR>
2.3.2 Boolean Operations --
            <tt class="keyword">and</tt>, <tt class="keyword">or</tt>, <tt class="keyword">not</tt>

</H2>

<P>
These are the Boolean operations, ordered by ascending priority:
<a id='l2h-104' xml:id='l2h-104'></a>
<P>
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      <th class="center">Operation</th>
      <th class="left"  >Result</th>
      <th class="center">Notes</th>
      </tr>
    </thead>
  <tbody>
    <tr><td class="center" valign="baseline"><code><var>x</var> or <var>y</var></code></td>
        <td class="left"  >if <var>x</var> is false, then <var>y</var>, else <var>x</var></td>
        <td class="center">(1)</td></tr>
    <tr><td class="center" valign="baseline"><code><var>x</var> and <var>y</var></code></td>
        <td class="left"  >if <var>x</var> is false, then <var>x</var>, else <var>y</var></td>
        <td class="center">(1)</td></tr>

    <tr><td class="center" valign="baseline"><code>not <var>x</var></code></td>
        <td class="left"  >if <var>x</var> is false, then <code>True</code>, else <code>False</code></td>
        <td class="center">(2)</td></tr></tbody>
</table></div>
<a id='l2h-105' xml:id='l2h-105'></a><a id='l2h-106' xml:id='l2h-106'></a><a id='l2h-107' xml:id='l2h-107'></a>
<P>
Notes:

<P>
<DL>
<DT><STRONG>(1)</STRONG></DT>
<DD>These only evaluate their second argument if needed for their outcome.

<P>
</DD>
<DT><STRONG>(2)</STRONG></DT>
<DD>"<tt class="samp">not</tt>" has a lower priority than non-Boolean operators, so
<code>not <var>a</var> == <var>b</var></code> is interpreted as <code>not (<var>a</var> ==
<var>b</var>)</code>, and <code><var>a</var> == not <var>b</var></code> is a syntax error.

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</DD>
</DL>

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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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