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| 17 | <title>2.3.2 Boolean Operations -- and, or, not </title> |
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| 55 | <H2><A NAME="SECTION004320000000000000000"></A><A NAME="boolean"></A> |
| 56 | <BR> |
| 57 | 2.3.2 Boolean Operations -- |
| 58 | <tt class="keyword">and</tt>, <tt class="keyword">or</tt>, <tt class="keyword">not</tt> |
| 59 | |
| 60 | </H2> |
| 61 | |
| 62 | <P> |
| 63 | These are the Boolean operations, ordered by ascending priority: |
| 64 | <a id='l2h-104' xml:id='l2h-104'></a> |
| 65 | <P> |
| 66 | <div class="center"><table class="realtable"> |
| 67 | <thead> |
| 68 | <tr> |
| 69 | <th class="center">Operation</th> |
| 70 | <th class="left" >Result</th> |
| 71 | <th class="center">Notes</th> |
| 72 | </tr> |
| 73 | </thead> |
| 74 | <tbody> |
| 75 | <tr><td class="center" valign="baseline"><code><var>x</var> or <var>y</var></code></td> |
| 76 | <td class="left" >if <var>x</var> is false, then <var>y</var>, else <var>x</var></td> |
| 77 | <td class="center">(1)</td></tr> |
| 78 | <tr><td class="center" valign="baseline"><code><var>x</var> and <var>y</var></code></td> |
| 79 | <td class="left" >if <var>x</var> is false, then <var>x</var>, else <var>y</var></td> |
| 80 | <td class="center">(1)</td></tr> |
| 81 | |
| 82 | <tr><td class="center" valign="baseline"><code>not <var>x</var></code></td> |
| 83 | <td class="left" >if <var>x</var> is false, then <code>True</code>, else <code>False</code></td> |
| 84 | <td class="center">(2)</td></tr></tbody> |
| 85 | </table></div> |
| 86 | <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> |
| 87 | <P> |
| 88 | Notes: |
| 89 | |
| 90 | <P> |
| 91 | <DL> |
| 92 | <DT><STRONG>(1)</STRONG></DT> |
| 93 | <DD>These only evaluate their second argument if needed for their outcome. |
| 94 | |
| 95 | <P> |
| 96 | </DD> |
| 97 | <DT><STRONG>(2)</STRONG></DT> |
| 98 | <DD>"<tt class="samp">not</tt>" has a lower priority than non-Boolean operators, so |
| 99 | <code>not <var>a</var> == <var>b</var></code> is interpreted as <code>not (<var>a</var> == |
| 100 | <var>b</var>)</code>, and <code><var>a</var> == not <var>b</var></code> is a syntax error. |
| 101 | |
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