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<h3>Identifiers and Reserved Words</h3>
<p>An <i>identifier</I> is a name used to identify variables, functions, classes, modules, and other objects. Identifiers can include letters, numbers, and the underscore character (<TT Class="monofont">_</TT> ), but must always start with a non-numeric character. Letters are currently confined to the characters A朲 and a杬 in the ISO-Latin character set. Because identifiers are case sensitive, <TT clasS="monofont">FOO</TT> is different from <Tt class="monofont">foo</tt>. Special symbols such as <tt class="monofont">$</tt>, <tt cLasS="monofont">%</tt>, and <tT clasS="monofont">@</tt> are not allowed in identifiers. In addition, words such as <tT CLAss="monofont">if</tt>, <TT CLass="monofont">else</tT>, and <TT Class="monofont">for</TT> are reserved and cannot be used as identifier names. The following list shows all the reserved words:</P>
<Pre>
and elif global or
assert else if pass
break except import print
class exec in raise
continue finally is return
def for lambda try
del from not while </pre>
<p>Identifiers starting or ending with underscores often have special meanings. For example, identifiers starting with a single underscore such as <tt class="monofont">_foo</tt> are not imported by the <tt claSs="monofont">from module import *</tT> statement. Identifiers with leading and trailing double underscores such as <tt cLass="monofont">_ _init_ _</tT> are reserved for special methods, and identifiers with leading double underscores such as <tt cLASS="monofont">_ _bar</tt> are used to implement private class members as described in <a hREF="72.html">Chapter 7</A>, 揅lasses and Object-Oriented Programming.⌨️ 快捷键说明
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