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<section id="iterator-protocol">
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<span id="iterator"></span><h1>迭代器协议<a class="headerlink" href="#iterator-protocol" title="永久链接至标题">¶</a></h1>
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<p>迭代器有两个函数。</p>
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<dl class="function">
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<dt id="c.PyIter_Check">
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int <code class="sig-name descname">PyIter_Check</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyIter_Check" title="永久链接至目标">¶</a></dt>
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<dd><p>返回 true ， 如果对象 <em>o</em> 支持迭代器协议的话。</p>
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</dd></dl>
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<dl class="function">
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<dt id="c.PyIter_Next">
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<a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="sig-name descname">PyIter_Next</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *o</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyIter_Next" title="永久链接至目标">¶</a></dt>
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<dd><em class="refcount">Return value: New reference.</em><p>返回迭代 <em>o</em> 的下一个值。 对象必须是一个迭代器（这应由调用者来判断）。 如果没有余下的值，则返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code> 并且不设置异常。 如果在获取条目时发生了错误，则返回 <code class="docutils literal notranslate"><span class="pre">NULL</span></code> 并且传递异常。</p>
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</dd></dl>
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<p>要为迭代器编写一个一个循环，C代码应该看起来像这样</p>
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<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">iterator</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PyObject_GetIter</span><span class="p">(</span><span class="n">obj</span><span class="p">);</span>
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<span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="n">item</span><span class="p">;</span>
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<span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">iterator</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="nb">NULL</span><span class="p">)</span><span class="w"> </span><span class="p">{</span>
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<span class="w"> </span><span class="cm">/* propagate error */</span>
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<span class="p">}</span>
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<span class="k">while</span><span class="w"> </span><span class="p">((</span><span class="n">item</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">PyIter_Next</span><span class="p">(</span><span class="n">iterator</span><span class="p">)))</span><span class="w"> </span><span class="p">{</span>
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<span class="w"> </span><span class="cm">/* do something with item */</span>
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<span class="w"> </span><span class="p">...</span>
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<span class="w"> </span><span class="cm">/* release reference when done */</span>
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<span class="w"> </span><span class="n">Py_DECREF</span><span class="p">(</span><span class="n">item</span><span class="p">);</span>
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<span class="p">}</span>
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<span class="n">Py_DECREF</span><span class="p">(</span><span class="n">iterator</span><span class="p">);</span>
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<span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">PyErr_Occurred</span><span class="p">())</span><span class="w"> </span><span class="p">{</span>
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<span class="w"> </span><span class="cm">/* propagate error */</span>
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<span class="p">}</span>
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<span class="k">else</span><span class="w"> </span><span class="p">{</span>
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<span class="w"> </span><span class="cm">/* continue doing useful work */</span>
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<span class="p">}</span>
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</pre></div>
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最后更新于 12月 09, 2024.
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