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<title>2.3.4.1 Bit-string Operations on Integer Types
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<H3><A NAME=
"SECTION004341000000000000000"></A><A NAME=
"bitstring-ops"></A>
2.3.4.1 Bit-string Operations on Integer Types
<A NAME=
"Bit-string_Operations"></A>
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).
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>").
This table lists the bit-string operations sorted in ascending
priority (operations in the same box have the same priority):
<div class=
"center"><table class=
"realtable">
<th class=
"center">Operation
</th>
<th class=
"left" >Result
</th>
<th class=
"center">Notes
</th>
<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> & <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> << <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> >> <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>
<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>
<DT><STRONG>(
1)
</STRONG></DT>
<DD>Negative shift counts are illegal and cause a
<tt class=
"exception">ValueError
</tt> to be raised.
<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.
<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.
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<span class=
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2005.
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