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<title>2.3.4.1 Bit-string Operations on Integer Types </title>
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<H3><A NAME="SECTION004341000000000000000"></A><A NAME="bitstring-ops"></A>
<BR>
2.3.4.1 Bit-string Operations on Integer Types
</H3>
<A NAME="Bit-string_Operations"></A>
<P>
Plain and long integer types support additional operations that make
sense only for bit-strings.  Negative numbers are treated as their 2's
complement value (for long integers, this assumes a sufficiently large
number of bits that no overflow occurs during the operation).

<P>
The priorities of the binary bit-wise operations are all lower than
the numeric operations and higher than the comparisons; the unary
operation "<tt class="samp">~</tt>" has the same priority as the other unary numeric
operations ("<tt class="samp">+</tt>" and "<tt class="samp">-</tt>").

<P>
This table lists the bit-string operations sorted in ascending
priority (operations in the same box have the same priority):

<P>
<div class="center"><table class="realtable">
  <thead>
    <tr>
      <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> | <var>y</var></code></td>
        <td class="left"  >bitwise <i class="dfn">or</i> of <var>x</var> and <var>y</var></td>
        <td class="center"></td></tr>
    <tr><td class="center" valign="baseline"><code><var>x</var> ^ <var>y</var></code></td>
        <td class="left"  >bitwise <i class="dfn">exclusive or</i> of <var>x</var> and <var>y</var></td>
        <td class="center"></td></tr>
    <tr><td class="center" valign="baseline"><code><var>x</var> &amp; <var>y</var></code></td>
        <td class="left"  >bitwise <i class="dfn">and</i> of <var>x</var> and <var>y</var></td>
        <td class="center"></td></tr>
    <tr><td class="center" valign="baseline"><code><var>x</var> &lt;&lt; <var>n</var></code></td>
        <td class="left"  ><var>x</var> shifted left by <var>n</var> bits</td>
        <td class="center">(1), (2)</td></tr>
    <tr><td class="center" valign="baseline"><code><var>x</var> &gt;&gt; <var>n</var></code></td>
        <td class="left"  ><var>x</var> shifted right by <var>n</var> bits</td>
        <td class="center">(1), (3)</td></tr>

    <tr><td class="center" valign="baseline"><code>~<var>x</var></code></td>
        <td class="left"  >the bits of <var>x</var> inverted</td>
        <td class="center"></td></tr></tbody>
</table></div>
<a id='l2h-148' xml:id='l2h-148'></a><a id='l2h-149' xml:id='l2h-149'></a><a id='l2h-150' xml:id='l2h-150'></a><a id='l2h-151' xml:id='l2h-151'></a>
<P>
Notes:
<DL>
<DT><STRONG>(1)</STRONG></DT>
<DD>Negative shift counts are illegal and cause a
<tt class="exception">ValueError</tt> to be raised.
</DD>
<DT><STRONG>(2)</STRONG></DT>
<DD>A left shift by <var>n</var> bits is equivalent to
multiplication by <code>pow(2, <var>n</var>)</code> without overflow check.
</DD>
<DT><STRONG>(3)</STRONG></DT>
<DD>A right shift by <var>n</var> bits is equivalent to
division by <code>pow(2, <var>n</var>)</code> without overflow check.
</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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