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<title>python经典面试题：列表和元组有什么异同？</title>
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<h1 class="entry-title">
<a href="/list_tuple_compare.html" rel="bookmark"
title="Permalink to python经典面试题：列表和元组有什么异同？">python经典面试题：列表和元组有什么异同？</a></h1>
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<abbr class="published" title="2018-11-27T05:20:00+08:00">
Published: 二 27 十一月 2018
</abbr>
<address class="vcard author">
By <a class="url fn" href="/author/andrew.html">andrew</a>
</address>
<p>In <a href="/category/python.html">python</a>.</p>
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<li><a href="https://china-testing.github.io/practices.html">python测试开发项目实战-目录</a></li>
<li><a href="https://china-testing.github.io/python_books.html">python工具书籍下载-持续更新</a></li>
<li><a href="https://china-testing.github.io/python3_quick.html">python 3.7极速入门教程 - 目录</a></li>
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<p>列表和元组是Python中最常用的两种数据结构，字典是第三种。 相同点：</p>
<ul>
<li>都是序列</li>
<li>都可以存储任何数据类型</li>
<li>可以通过索引访问</li>
</ul>
<p><img alt="图片.png" src="https://upload-images.jianshu.io/upload_images/12713060-32a6c6361069d513.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240"></p>
<h3 id="_1">语法差异</h3>
<p>使用方括号[]创建列表，而使用括号()创建元组。 请看以下示例：</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">l</span> <span class="o">=</span> <span class="p">[</span><span class="s2">"https://china-testing.github.io/"</span><span class="p">,</span> <span class="s2">"https://www.oscobo.com/"</span><span class="p">]</span>
<span class="o">>>></span> <span class="n">t</span> <span class="o">=</span> <span class="p">(</span><span class="s2">"https://china-testing.github.io/"</span><span class="p">,</span> <span class="s2">"https://www.oscobo.com/"</span><span class="p">)</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">l</span><span class="p">)</span>
<span class="p">[</span><span class="s1">'https://china-testing.github.io/'</span><span class="p">,</span> <span class="s1">'https://www.oscobo.com/'</span><span class="p">]</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">t</span><span class="p">)</span>
<span class="p">(</span><span class="s1">'https://china-testing.github.io/'</span><span class="p">,</span> <span class="s1">'https://www.oscobo.com/'</span><span class="p">)</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="nb">type</span><span class="p">(</span><span class="n">l</span><span class="p">))</span>
<span class="o"><</span><span class="k">class</span> <span class="err">'</span><span class="nc">list</span><span class="s1">'></span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="nb">type</span><span class="p">(</span><span class="n">t</span><span class="p">))</span>
<span class="o"><</span><span class="k">class</span> <span class="err">'</span><span class="nc">tuple</span><span class="s1">'></span>
</pre></div>
<h3 id="_2">是否可变</h3>
<p>列表是可变的，而元组是不可变的，这标志着两者之间的关键差异。 </p>
<p>我们可以修改列表的值，但是不修改元组的值。</p>
<p>由于列表是可变的，我们不能将列表用作字典中的key。 但可以使用元组作为字典key。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">l</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="s2">"https://www.jianshu.com/u/69f40328d4f0"</span>
<span class="o">>>></span> <span class="n">l</span>
<span class="p">[</span><span class="s1">'https://china-testing.github.io/'</span><span class="p">,</span> <span class="s1">'https://www.jianshu.com/u/69f40328d4f0'</span><span class="p">]</span>
<span class="o">>>></span> <span class="n">t</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="o">=</span> <span class="s2">"https://www.jianshu.com/u/69f40328d4f0"</span>
<span class="n">Traceback</span> <span class="p">(</span><span class="n">most</span> <span class="n">recent</span> <span class="n">call</span> <span class="n">last</span><span class="p">):</span>
<span class="n">File</span> <span class="s2">"<stdin>"</span><span class="p">,</span> <span class="n">line</span> <span class="mi">1</span><span class="p">,</span> <span class="ow">in</span> <span class="o"><</span><span class="n">module</span><span class="o">></span>
<span class="ne">TypeError</span><span class="p">:</span> <span class="s1">'tuple'</span> <span class="nb">object</span> <span class="n">does</span> <span class="ow">not</span> <span class="n">support</span> <span class="n">item</span> <span class="n">assignment</span>
</pre></div>
<h3 id="_3">重用与拷贝</h3>
<p>元组无法复制。 原因是元组是不可变的。 如果运行tuple(tuple_name)将返回自己。 </p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">copy_t</span> <span class="o">=</span> <span class="nb">tuple</span><span class="p">(</span><span class="n">t</span><span class="p">)</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">t</span> <span class="ow">is</span> <span class="n">copy_t</span><span class="p">)</span>
<span class="bp">True</span>
<span class="o">>>></span> <span class="n">copy_l</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="n">l</span><span class="p">)</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">l</span> <span class="ow">is</span> <span class="n">copy_l</span><span class="p">)</span>
<span class="bp">False</span>
</pre></div>
<h3 id="_4">参考资料</h3>
<ul>
<li>讨论 qq群144081101 567351477</li>
<li><a href="https://china-testing.github.io/list_tuple_compare.html">本文最新版本地址</a></li>
<li><a href="https://github.com/china-testing/python-api-tesing">本文涉及的python测试开发库</a> 谢谢点赞！</li>
<li><a href="https://github.com/china-testing/python-api-tesing/blob/master/books.md">本文相关海量书籍下载</a> </li>
<li><a href="https://china-testing.github.io/python_books.html">python工具书籍下载-持续更新</a></li>
</ul>
<h3 id="_5">大小差异</h3>
<p>Python将低开销的较大的块分配给元组，因为它们是不可变的。 对于列表则分配小内存块。 与列表相比，元组的内存更小。 当你拥有大量元素时，元组比列表快。列表的长度是可变的。</p>
<div class="highlight"><pre><span></span><span class="o">>>></span> <span class="n">l</span> <span class="o">=</span> <span class="p">[</span><span class="s2">"https://china-testing.github.io/"</span><span class="p">,</span> <span class="s2">"https://www.oscobo.com/"</span><span class="p">]</span>
<span class="o">>>></span> <span class="n">t</span> <span class="o">=</span> <span class="p">(</span><span class="s2">"https://china-testing.github.io/"</span><span class="p">,</span> <span class="s2">"https://www.oscobo.com/"</span><span class="p">)</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">l</span><span class="o">.</span><span class="n">__sizeof__</span><span class="p">())</span>
<span class="mi">56</span>
<span class="o">>>></span> <span class="k">print</span><span class="p">(</span><span class="n">t</span><span class="o">.</span><span class="n">__sizeof__</span><span class="p">())</span>
<span class="mi">40</span>
</pre></div>
<h3 id="_6">同构与异构</h3>
<p>习惯上元组多用于用于存储异构元素，异构元素即不同数据类型的元素，比如(ip,port)。 另一方面，列表用于存储异构元素，这些元素属于相同类型的元素，比如[int1,in2,in3]。</p>
<h3 id="_7">参考资料</h3>
<ul>
<li>讨论qq群630011153 144081101</li>
<li><a href="https://china-testing.github.io/list_tuple_compare.html">本文最新版本地址</a></li>
<li><a href="https://github.com/china-testing/python-api-tesing">本文涉及的python测试开发库</a> 谢谢点赞！</li>
<li><a href="https://github.com/china-testing/python-api-tesing/blob/master/books.md">本文相关海量书籍下载</a> </li>
<li>道家技术-手相手诊看相中医等钉钉群21734177 qq群：391441566 184175668 338228106 看手相、面相、舌相、抽签、体质识别。服务费50元每人次起。请联系钉钉或者微信pythontesting</li>
<li><a href="https://china-testing.github.io/testing_training.html">接口自动化性能测试线上培训大纲</a></li>
<li><a href="https://www.fullstackpython.com/monitoring.html">Monitoring</a></li>
<li><a href="https://www.jianshu.com/p/49202312f855">2018最佳人工智能机器学习工具书及下载(持续更新)</a></li>
<li>https://github.com/lorien/awesome-web-scraping/blob/master/python.md</li>
<li>最好用的Python爬虫推荐 https://www.jianshu.com/p/7da43c16dd87</li>
<li>https://www.zhihu.com/question/41277528</li>
</ul>
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<h2>links</h2>
<ul>
<li><a href="https://china-testing.github.io/testing_training.html">自动化性能接口测试线上及深圳培训与项目实战 qq群：144081101 591302926</a></li>
<li><a href="http://blog.sciencenet.cn/blog-2604609-1112306.html">pandas数据分析scrapy爬虫 521070358 Py人工智能pandas-opencv 6089740</a></li>
<li><a href="http://blog.sciencenet.cn/blog-2604609-1112306.html">中医解梦看相八字算命qq群 391441566 csdn书籍下载-python爬虫 437355848</a></li>
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