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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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