jacksoncode.github.io/tutorials/python/7.html at master · jacksoncode/jacksoncode.github.io

Repository navigation

History

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

<!DOCTYPE html>

<head>

<title>5. Python基础 - CodeClub</title>

<style>

.tutorial-container { max-width: 960px; margin: 70px auto 40px; padding: 0 20px; }

.tutorial-sidebar { position: fixed; top: 70px; left: 20px; width: 260px; max-height: calc(100vh - 90px); overflow-y: auto; background: var(--bg-secondary, #fff); border-radius: 8px; padding: 16px; box-shadow: 0 2px 8px rgba(0,0,0,0.08); }

.tutorial-sidebar h3 { font-size: 16px; margin-bottom: 12px; color: var(--text-primary, #1a1a2e); }

.tutorial-sidebar a { display: block; padding: 6px 10px; color: var(--text-secondary, #666); text-decoration: none; font-size: 14px; border-radius: 4px; }

.tutorial-sidebar a:hover, .tutorial-sidebar a.active { background: var(--primary, #3b82f6); color: #fff; }

.tutorial-sidebar .sub-link { padding-left: 24px; font-size: 13px; }

.tutorial-content { margin-left: 300px; background: var(--bg-secondary, #fff); border-radius: 8px; padding: 32px; box-shadow: 0 2px 8px rgba(0,0,0,0.08); }

.tutorial-content h1 { font-size: 28px; margin-bottom: 20px; color: var(--text-primary, #1a1a2e); border-bottom: 2px solid var(--primary, #3b82f6); padding-bottom: 12px; }

.tutorial-content h2 { font-size: 22px; margin: 24px 0 16px; color: var(--text-primary, #1a1a2e); }

.tutorial-content h3 { font-size: 18px; margin: 20px 0 12px; }

.tutorial-content p { line-height: 1.8; margin: 12px 0; color: var(--text-secondary, #333); }

.tutorial-content pre { background: #1e1e2e; color: #cdd6f4; padding: 16px; border-radius: 8px; overflow-x: auto; margin: 16px 0; }

.tutorial-content code { font-family: 'Fira Code', 'Cascadia Code', monospace; font-size: 14px; }

.tutorial-content p code { background: #f1f5f9; padding: 2px 6px; border-radius: 4px; color: #e83e8c; }

.tutorial-content blockquote { border-left: 4px solid var(--primary, #3b82f6); padding: 12px 20px; margin: 16px 0; background: #f8fafc; border-radius: 0 8px 8px 0; }

.tutorial-content ul, .tutorial-content ol { padding-left: 24px; margin: 12px 0; }

.tutorial-content li { margin: 6px 0; line-height: 1.7; }

.tutorial-content img { max-width: 100%; border-radius: 8px; margin: 16px 0; }

.tutorial-nav { display: flex; justify-content: space-between; margin-top: 32px; padding-top: 20px; border-top: 1px solid var(--border, #e5e7eb); }

.tutorial-nav a { color: var(--primary, #3b82f6); text-decoration: none; font-weight: 500; }

.tutorial-nav a:hover { text-decoration: underline; }

.tutorial-index { max-width: 960px; margin: 70px auto 40px; padding: 0 20px; }

.tutorial-card { background: var(--bg-secondary, #fff); border-radius: 12px; padding: 24px; margin: 16px 0; box-shadow: 0 2px 8px rgba(0,0,0,0.08); transition: transform 0.2s; }

.tutorial-card:hover { transform: translateY(-2px); }

.tutorial-card h3 { margin: 0 0 8px; color: var(--text-primary, #1a1a2e); }

.tutorial-card p { color: var(--text-secondary, #666); margin: 0 0 12px; }

.tutorial-card .badge { display: inline-block; padding: 4px 10px; border-radius: 20px; font-size: 12px; font-weight: 600; margin-right: 8px; }

.badge-python { background: #3b82f6; color: #fff; }

.badge-git { background: #f97316; color: #fff; }

.badge-ai { background: #8b5cf6; color: #fff; }

@media (max-width: 768px) {

.tutorial-sidebar { display: none; }

.tutorial-content { margin-left: 0; }

}

</style>

</head>

<body>

<span>CodeClub</span>

</a>

</button>

</ul>

</div>

</nav>

<div class="tutorial-container" style="max-width: 960px; margin: 80px auto 40px; padding: 0 20px;"><div class="tutorial-sidebar"><h3>目录</h3><a href="0.html">1. 简介</a><a href="1.html">2. Python历史</a><a href="2.html">3. 安装Python</a><a href="3.html">3.1. Python解释器</a><a href="4.html">4. 第一个Python程序</a><a href="5.html">4.1. 使用文本编辑器</a><a href="6.html">4.2. 输入和输出</a><a href="7.html">5. Python基础</a><a href="8.html">5.1. 数据类型和变量</a><a href="9.html">5.2. 字符串和编码</a><a href="10.html">5.3. 使用list和tuple</a><a href="11.html">5.4. 条件判断</a><a href="12.html">5.5. 模式匹配</a><a href="13.html">5.6. 循环</a><a href="14.html">5.7. 使用dict和set</a><a href="15.html">6. 函数</a><a href="16.html">6.1. 调用函数</a><a href="17.html">6.2. 定义函数</a><a href="18.html">6.3. 函数的参数</a><a href="19.html">6.4. 递归函数</a><a href="20.html">7. 高级特性</a><a href="21.html">7.1. 切片</a><a href="22.html">7.2. 迭代</a><a href="23.html">7.3. 列表生成式</a><a href="24.html">7.4. 生成器</a><a href="25.html">7.5. 迭代器</a><a href="26.html">8. 函数式编程</a><a href="27.html">8.1. 高阶函数</a><a href="28.html">8.1.1. map/reduce</a><a href="29.html">8.1.2. filter</a><a href="30.html">8.1.3. sorted</a><a href="31.html">8.2. 返回函数</a><a href="32.html">8.3. 匿名函数</a><a href="33.html">8.4. 装饰器</a><a href="34.html">8.5. 偏函数</a><a href="35.html">9. 模块</a><a href="36.html">9.1. 使用模块</a><a href="37.html">9.2. 安装第三方模块</a><a href="38.html">10. 面向对象编程</a><a href="39.html">10.1. 类和实例</a><a href="40.html">10.2. 访问限制</a><a href="41.html">10.3. 继承和多态</a><a href="42.html">10.4. 获取对象信息</a><a href="43.html">10.5. 实例属性和类属性</a><a href="44.html">11. 面向对象高级编程</a><a href="45.html">11.1. 使用__slots__</a><a href="46.html">11.2. 使用@property</a><a href="47.html">11.3. 多重继承</a><a href="48.html">11.4. 定制类</a><a href="49.html">11.5. 使用枚举类</a><a href="50.html">11.6. 使用元类</a><a href="51.html">12. 错误、调试和测试</a><a href="52.html">12.1. 错误处理</a><a href="53.html">12.2. 调试</a><a href="54.html">12.3. 单元测试</a><a href="55.html">12.4. 文档测试</a><a href="56.html">13. IO编程</a><a href="57.html">13.1. 文件读写</a><a href="58.html">13.2. StringIO和BytesIO</a><a href="59.html">13.3. 操作文件和目录</a><a href="60.html">13.4. 序列化</a><a href="61.html">14. 进程和线程</a><a href="62.html">14.1. 多进程</a><a href="63.html">14.2. 多线程</a><a href="64.html">14.3. ThreadLocal</a><a href="65.html">14.4. 进程 vs. 线程</a><a href="66.html">14.5. 分布式进程</a><a href="67.html">15. 正则表达式</a><a href="68.html">16. 常用内建模块</a><a href="69.html">16.1. datetime</a><a href="70.html">16.2. collections</a><a href="71.html">16.3. argparse</a><a href="72.html">16.4. base64</a><a href="73.html">16.5. struct</a><a href="74.html">16.6. hashlib</a><a href="75.html">16.7. hmac</a><a href="76.html">16.8. itertools</a><a href="77.html">16.9. contextlib</a><a href="78.html">16.10. urllib</a><a href="79.html">16.11. XML</a><a href="80.html">16.12. HTMLParser</a><a href="81.html">16.13. venv</a><a href="82.html">17. 常用第三方模块</a><a href="83.html">17.1. Pillow</a><a href="84.html">17.2. requests</a><a href="85.html">17.3. chardet</a><a href="86.html">17.4. psutil</a><a href="87.html">18. 图形界面</a><a href="88.html">18.1. 海龟绘图</a><a href="89.html">19. 网络编程</a><a href="90.html">19.1. TCP/IP简介</a><a href="91.html">19.2. TCP编程</a><a href="92.html">19.3. UDP编程</a><a href="93.html">20. 电子邮件</a><a href="94.html">20.1. SMTP发送邮件</a><a href="95.html">20.2. POP3收取邮件</a><a href="96.html">21. 访问数据库</a><a href="97.html">21.1. 使用SQLite</a><a href="98.html">21.2. 使用MySQL</a><a href="99.html">21.3. 使用SQLAlchemy</a><a href="100.html">22. Web开发</a><a href="101.html">22.1. HTTP协议简介</a><a href="102.html">22.2. HTML简介</a><a href="103.html">22.3. WSGI接口</a><a href="104.html">22.4. 使用Web框架</a><a href="105.html">22.5. 使用模板</a><a href="106.html">23. 异步IO</a><a href="107.html">23.1. 协程</a><a href="108.html">23.2. 使用asyncio</a><a href="109.html">23.3. 使用aiohttp</a><a href="110.html">24. FAQ</a><a href="111.html">25. 期末总结</a></div><div class="tutorial-content"><h1>5. Python基础</h1><div class="tutorial-body"><p>Python的语法比较简单，采用缩进方式，写出来的代码就像下面的样子：</p>

<pre class="hljs"><code class="language-python"><span class="hljs-comment"># print absolute value of an integer:</span>

a = <span class="hljs-number">100</span>

<span class="hljs-keyword">if</span> a >= <span class="hljs-number">0</span>:

<span class="hljs-built_in">print</span>(a)

<span class="hljs-keyword">else</span>:

<span class="hljs-built_in">print</span>(-a)

</code></pre>

<p>以<code>#</code>开头的语句是注释，注释是给人看的，可以是任意内容，解释器会忽略掉注释。其他每一行都是一个语句，当语句以冒号<code>:</code>结尾时，缩进的语句视为代码块。</p>

<p>缩进有利有弊。好处是强迫你写出格式化的代码，但没有规定缩进是几个空格还是Tab。按照约定俗成的惯例，应该始终坚持使用<em>4个空格</em>的缩进。</p>

<p>缩进的另一个好处是强迫你写出缩进较少的代码，你会倾向于把一段很长的代码拆分成若干函数，从而得到缩进较少的代码。</p>

<p>缩进的坏处就是“复制－粘贴”功能失效了，这是最坑爹的地方。当你重构代码时，粘贴过去的代码必须重新检查缩进是否正确。此外，IDE很难像格式化Java代码那样格式化Python代码。</p>

<p>最后，请务必注意，Python程序是<em>大小写敏感</em>的，如果写错了大小写，程序会报错。</p>

<p>Python使用缩进来组织代码块，请务必遵守约定俗成的习惯，坚持使用4个空格的缩进；</p>

<p>在文本编辑器中，需要设置把Tab自动转换为4个空格，确保不混用Tab和空格。</p>

</div>

<a href="/books/python/first-program/input-output/index.html"

onclick="gs_load_chapter('/books/python/first-program/input-output/index.html',true);return false;"

class="inline-block my-2">

stroke="currentColor">

<path stroke-linecap="round" stroke-linejoin="round"

d="M18.75 19.5l-7.5-7.5 7.5-7.5m-6 15L5.25 12l7.5-7.5" />

</svg>

输入和输出

</a>

</div>

<a href="/books/python/basic/data-types/index.html"

onclick="gs_load_chapter('/books/python/basic/data-types/index.html',true);return false;"

class="inline-block my-2">

数据类型和变量

stroke="currentColor">

<path stroke-linecap="round" stroke-linejoin="round"

d="M11.25 4.5l7.5 7.5-7.5 7.5m-6-15l7.5 7.5-7.5 7.5" />

</svg>

</a></div><div style="display: flex; justify-content: space-between; margin-top: 32px; padding-top: 20px; border-top: 1px solid var(--border, #e5e7eb);"><a href="6.html" style="color: var(--primary, #3b82f6); text-decoration: none; font-weight: 500;">← 4.2. 输入和输出</a><a href="8.html" style="color: var(--primary, #3b82f6); text-decoration: none; font-weight: 500;">5.1. 数据类型和变量 →</a></div><p style="margin-top: 16px; font-size: 13px; color: var(--text-secondary, #999);">原文：<a href="https://liaoxuefeng.com/books/python/basic/index.html" style="color: var(--primary, #3b82f6);">廖雪峰 - 5. Python基础</a></p></div></div>

</div>

</footer>

</body>

</html>

FilesExpand file tree

7.html

Latest commit

History

7.html

File metadata and controls