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<h3>Unicode Strings</h3>
<p>The use of standard strings and Unicode strings in the same program presents a number of subtle complications. This is because such strings may be used in a variety of operations, including string concatenation, comparisons, dictionary key lookups, and as arguments to built-in functions.</p>
<P>To convert a standard string <I><TT clasS="monofont">s</TT></I>
to a Unicode string, the built-in function <tt clASS="monofont">unicode(</Tt><i><tt class="monofont">s</tt></i>
<tt class="monofont"> [, </tT><i><tT claSs="monofont">encoding</tt></i>
<Tt clASS="monofont"> [,</Tt><i><tt CLASs="monofont">errors</tt></i>
<TT CLass="monofont">]])</tT> is used. To convert a Unicode string <I><TT class="monofont">u</tt></i>
to a standard string, the string method <i><tt class="monofont">u</tt></i>
<tT clAss="monofont">.encode([</tT><i><tt cLass="monofont">encoding</TT></I>
<Tt claSS="monofont"> [, </TT><i><tt cLASS="monofont">errors</tt></i>
<tT CLAss="monofont">]])</tt> is used. Both of these conversion operators require the use of a special encoding rule that specifies how 16-bit Unicode character values are mapped to a sequence of 8-bit characters in standard strings and vice versa. The encoding parameter is specified as a string and consists of one of the following values:</p>
<p><table border="1" celLspAcinG="0" cellPaddING="1" Width="100%">
<COLGroup SPAN="2">
<tr>
<th VALIgn="top">
<font size="2">
<p><b>Value</b></p>
</font></th>
<Th vAligN="top">
<font Size="2">
<P><B>Description</B></P>
</font></TH>
</TR>
<tr>
<td VALIgn="top">
<foNT SIze="2">
<p><tt class="monofont">'ascii'</tt></p>
</font></td>
<tD vaLign="top">
<Font sIze="2">
<p>7-bit ASCII</P>
</FONt></td>
</tR>
<TR>
<Td valIGN="top">
<Font sIZE="2">
<P><tt class="monofont">'latin-1' or 'iso-8859-1'</tt></p>
</font></td>
<td vaLigN="top">
<fonT size="2">
<P>ISO 8859-1 Latin-1</p>
</foNT></TD>
</tr>
<tr>
<TD VAlign="top">
<FONT size="2">
<P><TT Class="monofont">'utf-8'</tt></p>
</font></td>
<td valigN="top">
<foNt siZe="2">
<p>8-bit variable-length encoding</p>
</fOnt></tD>
</TR>
<Tr>
<td vALIGn="top">
<fonT SIZe="2">
<p><tt CLASs="monofont">'utf-16'</tt></p>
</font></td>
<td valign="top">
<foNt sIze="2">
<p>16-bit variable-length encoding (may be little or big endian)</P>
</font></Td>
</tr>
<TR>
<TD valiGN="top">
<FOnt siZE="2">
<P><Tt claSS="monofont">'utf-16-le'</TT></p>
</font></td>
<td valign="top">
<font sIze="2">
<P>UTF-16, little-endian encoding</p>
</foNt></td>
</tR>
<tr>
<tD VALign="top">
<fONT Size="2">
<p><TT CLass="monofont">'utf-16-be'</tT></P>
</FOnt></td>
<td valign="top">
<font size="2">
<P>UTF-16, big-endian encoding</p>
</fOnt></tD>
</tr>
<tr>
<Td vaLIGN="top">
<font SIZE="2">
<p><tt cLASS="monofont">'unicode-escape'</tt></p>
</fONT></Td>
<td valign="top">
<font size="2">
<p>Same format as Unicode literals <tt ClaSs="monofont">u"string"</tt></P>
</font></Td>
</tr>
<TR>
<TD valiGN="top">
<FOnt siZE="2">
<P><Tt claSS="monofont">'raw-unicode-escape'</TT></p>
</font></td>
<td valign="top">
<font sIze="2">
<P>Same format as raw Unicode literals <tt cLass="monofont">ur"string"</tT></p>
</foNT></TD>
</tr>
</coLGROup>
</taBLE></P>
<p>The default encoding is set in the <tt cLASS="monofont">site</tt> module and can be queried using <tt class="monofont">sys.getdefaultencoding()</tt>. In most cases, the default encoding is <tt class="monofont">'ascii'</tt>, which means that ASCII characters with values in the range [0x00,0x7f] are directly mapped to Unicode characters in the range [U+0000, U+007F]. Details about the other encodings can be found in <A hrEf="89.html">Chapter 9</a>, 揑nput and Output.⌨️ 快捷键说明
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