Python 3 备忘清单 === Python 备忘单是 [Python 3](https://www.python.org/) 编程语言的单页参考表 入门 ----- ### 介绍 - [Python 官方网站](https://www.python.org/) _(python.org)_ - [Python 文档](https://docs.python.org/zh-cn/3/index.html) _(docs.python.org)_ - [Y 分钟学会 Python](https://learnxinyminutes.com/docs/zh-cn/python-cn/) _(learnxinyminutes.com)_ - [Python 中的正则表达式](./regex.md#python-中的正则表达式) _(jaywcjlove.github.io)_ ### 控制台打印 ```python >>> print("Hello, World!") Hello, World! ``` 著名的“Hello World”程序在 Python 中的实现 ### 变量 ```python age = 18 # 年龄是 int 类型 name = "John" # 名字现在是 str 类型 print(name) ``` - Python 不能在没有赋值的情况下声明变量 - 变量可以存放不同类型的值 ### 内置数据类型 序列指一批有序的元素，集合指一批无序且不重复的元素 | :- | :- | |:----------------------------------------|:-----------------| | `str` | 文本／字符串（Text） | | `int`, `float`, `complex` | 数值（Numeric） | | `dict` | 映射／键值对（Mapping） | | `list`, `tuple`, `range` | 序列（Sequence） | | `set`, `frozenset` | 集合（Set） | | `bool` | 布尔值／逻辑值（Boolean） | | `bytes`, `bytearray`,
`memoryview` | 二进制数据（Binary） | 查看: [数据类型](#python-数据类型) ### 字符串切片 ```python >>> msg = "Hello, World!" >>> print(msg[2:5]) llo ``` 查看: [字符串](#python-字符串) ### 列表 ```python mylist = [] mylist.append(1) mylist.append(2) for item in mylist: print(item) # 打印输出 1,2 ``` 查看: [列表](#python-列表) ### 判断 ```python num = 200 if num > 0: print("num is greater than 0") else: print("num is not greater than 0") ``` 查看: [判断](#python-判断) ### 循环 ```python for item in range(6): if item == 3: break print(item) else: print("Finally finished!") ``` 查看: [循环](#python-循环) ### 函数 ```python >>> def my_function(): ... print("来自函数的你好") ... >>> my_function() 来自函数的你好 ``` 查看: [函数](#函数) ### 文件处理 ```python with open("myfile.txt", "r", encoding='utf8') as file: for line in file: print(line) ``` 查看: [文件处理](#python-文件处理) ### 算术 ```python result = 10 + 30 # => 40 result = 40 - 10 # => 30 result = 50 * 5 # => 250 result = 16 / 4 # => 4.0 (Float Division) result = 16 // 4 # => 4 (Integer Division) result = 25 % 2 # => 1 result = 5 ** 3 # => 125 ``` `/` 表示 x 和 y 的商，`//` 表示 x 和 y 的底商，另见 [StackOverflow](https://stackoverflow.com/a/183870/13192320) ### 加等于 ```python counter = 0 counter += 10 # => 10 counter = 0 counter = counter + 10 # => 10 message = "Part 1." # => Part 1.Part 2. message += "Part 2." ``` ### f-字符串 (Python 3.6+) ```python >>> website = 'Quick Reference' >>> f"Hello, {website}" "Hello, Quick Reference" >>> num = 10 >>> f'{num} + 10 = {num + 10}' '10 + 10 = 20' ``` 查看: [f-字符串](#python-f-字符串-python-36) Python 数据类型 --------------- ### 字符串 ```python hello = "Hello World" hello = 'Hello World' multi_string = """Multiline Strings Lorem ipsum dolor sit amet, consectetur adipiscing elit """ ``` 查看: [字符串](#python-字符串) ### 数值 ```python x = 1 # 整数 y = 2.8 # 浮点小数 z = 1j # 复数 >>> print(type(x)) ``` 只要内存足够，可以容纳无限大(小)的数值 ### 布尔值 ```python my_bool = True my_bool = False bool(0) # => False bool(1) # => True ``` bool 是 int 的子类 ### 列表 ```python list1 = ["apple", "banana", "cherry"] list2 = [True, False, False] list3 = [1, 5, 7, 9, 3] list4 = list((1, 5, 7, 9, 3)) ``` 查看: [列表](#python-列表) ### 元组 ```python my_tuple = (1, 2, 3) my_tuple = tuple((1, 2, 3)) ``` 类似列表，但自身不可变 ### 集合 ```python set1 = {"a", "b", "c"} set2 = set(("a", "b", "c")) ``` 类似列表，但里面的元素是无序而不重复的 ### 字典 ```python >>> empty_dict = {} >>> a = {"one": 1, "two": 2, "three": 3} >>> a["one"] 1 >>> a.keys() dict_keys(['one', 'two', 'three']) >>> a.values() dict_values([1, 2, 3]) >>> a.update({"four": 4}) >>> a.keys() dict_keys(['one', 'two', 'three', 'four']) >>> a['four'] 4 ``` 键-值对，一种像 JSON 那样对象 ### 类型转换 #### 转换为整数 ```python x = int(1) # 得到 1 y = int(2.8) # 得到 2 z = int("3") # 得到 3 ``` #### 转换为浮点数 ```python x = float(1) # 得到 1.0 y = float(2.8) # 得到 2.8 z = float("3") # 得到 3.0 w = float("4.2") # 得到 4.2 ``` #### 转换为字符串 ```python x = str("s1") # 得到 "s1" y = str(2) # 得到 "2" z = str(3.0) # 得到 "3.0" ``` Python 字符串 ------------ ### 下标访问 ```python >>> hello = "Hello, World" >>> print(hello[1]) # 获取第二个字符 e >>> print(hello[-1]) # 获取倒数第一个字符 d >>> print(type(hello[-1])) # 得到的还是字符串 ``` ### 循环 ```python >>> for char in "foo": ... print(char) f o o ``` 对字符串 for-in 可以得到每个字符（类型还是字符串） ### 切割字符串 ```java ┌───┬───┬───┬───┬───┬───┬───┐ | m | y | b | a | c | o | n | └───┴───┴───┴───┴───┴───┴───┘ 0 1 2 3 4 5 6 7 -7 -6 -5 -4 -3 -2 -1 ``` --- ```python >>> s = 'mybacon' >>> s[2:5] 'bac' >>> s[0:2] 'my' ``` --- ```python >>> s = 'mybacon' >>> s[:2] 'my' >>> s[2:] 'bacon' >>> s[:2] + s[2:] 'mybacon' >>> s[:] 'mybacon' ``` --- ```python >>> s = 'mybacon' >>> s[-5:-1] 'baco' >>> s[2:6] 'baco' ``` #### 步长 ```python >>> s = '12345' * 5 >>> s '1234512345123451234512345' >>> s[::5] '11111' >>> s[4::5] '55555' >>> s[::-5] '55555' >>> s[::-1] '5432154321543215432154321' ``` ### 获取长度 ```python >>> hello = "Hello, World!" >>> print(len(hello)) 13 ``` `len()` 函数返回字符串的长度 ### 重复多次 ```python >>> s = '===+' >>> n = 8 >>> s * n '===+===+===+===+===+===+===+===+' ``` ### 存在性判断 ```python >>> s = 'spam' >>> s in 'I saw spamalot!' True >>> s not in 'I saw The Holy Grail!' True ``` 判断 "spam" 这个字符串是否在其它字符串里 ### 字符串拼接 ```python >>> s = 'spam' >>> t = 'egg' >>> s + t # 可以使用加号进行拼接 'spamegg' >>> 'spam' 'egg' # 两个字符串之间可以省略加号 'spamegg' ``` ### 格式化 ```python name = "John" print("Hello, %s!" % name) ``` --- ```python name = "John" age = 23 print("%s is %d years old." % (name, age)) ``` #### format() 方法 ```python txt1 = "My name is {fname}, I'm {age}".format(fname="John", age=36) txt2 = "My name is {0}, I'm {1}".format("John", 36) txt3 = "My name is {}, I'm {}".format("John", 36) ``` ### 控制台输入 ```python >>> name = input("Enter your name: ") Enter your name: Tom >>> name 'Tom' ``` 从控制台获取输入数据 ### 插入分隔符拼接 ```python >>> "、".join(["John", "Peter", "Vicky"]) 'John、Peter、Vicky' ``` ### 头尾判断 ```python >>> # 是否以 H 开头 >>> "Hello, world!".endswith("H") True >>> # 是否以 h 开头 >>> "Hello, world!".endswith("h") False >>> # 是否以 ! 结尾 >>> "Hello, world!".endswith("!") True ``` ### 转义符号 | 转义符号 | 对应的操作 | |------|--------| | `\\` | 输出反斜杠 | | `\'` | 输出单引号 | | `\"` | 输出双引号 | | `\n` | 换行 | | `\t` | 水平制表符 | | `\r` | 光标回到首位 | | `\b` | 退格 | Python f-字符串 (Python 3.6+) ---------------- ### f-字符串 用法 ```python >>> website = 'Reference' >>> f"Hello, {website}" "Hello, Reference" >>> num = 10 >>> f'{num} + 10 = {num + 10}' '10 + 10 = 20' >>> f"""He said {"I'm John"}""" "He said I'm John" >>> f'5 {"{stars}"}' '5 {stars}' >>> f'{{5}} {"stars"}' '{5} stars' >>> name = 'Eric' >>> age = 27 >>> f"""Hello! ... I'm {name}. ... I'm {age}.""" "Hello!\n I'm Eric.\n I'm 27." ``` 它从 Python 3.6 开始可用，另见: [格式字符串字面值](https://docs.python.org/zh-cn/3/reference/lexical_analysis.html#f-strings) ### 填充对齐 ```python >>> f'{"text":10}' # 使用空格填充到指定长度 'text ' >>> f'{"test":*>10}' # 向左填充 '******test' >>> f'{"test":*<10}' # 向右填充 'test******' >>> f'{"test":*^10}' # 居中填充 '***test***' >>> f'{12345:0>10}' # 使用数字填充 '0000012345' ``` ### 按类型输出 ```python >>> f'{10:b}' # 输出二进制数值 '1010' >>> f'{10:o}' # 输出八进制数值 '12' >>> f'{200:x}' # 输出十六进制数值 'c8' >>> f'{200:X}' 'C8' >>> f'{345600000000:e}' # 科学计数法 '3.456000e+11' >>> f'{65:c}' # 将整数转化为一个字符后输出 'A' >>> f'{10:#b}' # [类型] 带符号（基础） '0b1010' >>> f'{10:#o}' '0o12' >>> f'{10:#x}' '0xa' ``` ### 显示正负号 ```python >>> f'{12345:+}' # 显示正数的正号 '+12345' >>> f'{-12345:+}' # 显示负数的负号 '-12345' >>> f'{-12345:+10}' # 显示负号，并使用空格填充，直到长度为 10 ' -12345' >>> f'{-12345:+010}' # 显示负号，并使用0填充，直到长度为 10 '-000012345' ``` ### 其它 ```python >>> f'{-12345:0=10}' # 负数 '-000012345' >>> f'{12345:010}' # [0] 快捷方式（不对齐） '0000012345' >>> f'{-12345:010}' '-000012345' >>> import math # [.precision] >>> math.pi 3.141592653589793 >>> f'{math.pi:.2f}' '3.14' >>> f'{1000000:,.2f}' # [分组选项] '1,000,000.00' >>> f'{1000000:_.2f}' '1_000_000.00' >>> f'{0.25:0%}' # 百分比 '25.000000%' >>> f'{0.25:.0%}' '25%' ``` Python 列表 ------------ ### 定义 ```python >>> li1 = [] >>> li1 [] >>> li2 = [4, 5, 6] >>> li2 [4, 5, 6] >>> li3 = list((1, 2, 3)) >>> li3 [1, 2, 3] >>> li4 = list(range(1, 11)) >>> li4 [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] ``` ### 生成 ```python >>> list(filter(lambda x : x % 2 == 1, range(1, 20))) [1, 3, 5, 7, 9, 11, 13, 15, 17, 19] >>> [x ** 2 for x in range (1, 11) if x % 2 == 1] [1, 9, 25, 49, 81] >>> [x for x in [3, 4, 5, 6, 7] if x > 5] [6, 7] >>> list(filter(lambda x: x > 5, [3, 4, 5, 6, 7])) [6, 7] ``` ### 添加元素 ```python >>> li = [] >>> li.append(1) >>> li [1] >>> li.append(2) >>> li [1, 2] >>> li.append(4) >>> li [1, 2, 4] >>> li.append(3) >>> li [1, 2, 4, 3] ``` ### 切片 列表切片的语法： ```python a_list[start:end] a_list[start:end:step] ``` #### 切片 ```python >>> a = ['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster'] >>> a[2:5] ['bacon', 'tomato', 'ham'] >>> a[-5:-2] ['egg', 'bacon', 'tomato'] >>> a[1:4] ['egg', 'bacon', 'tomato'] ``` #### 省略索引 ```python >>> a[:4] ['spam', 'egg', 'bacon', 'tomato'] >>> a[0:4] ['spam', 'egg', 'bacon', 'tomato'] >>> a[2:] ['bacon', 'tomato', 'ham', 'lobster'] >>> a[2:len(a)] ['bacon', 'tomato', 'ham', 'lobster'] >>> a ['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster'] >>> a[:] ['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster'] ``` #### 间隔索引 ```python ['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster'] >>> a[0:6:2] ['spam', 'bacon', 'ham'] >>> a[1:6:2] ['egg', 'tomato', 'lobster'] >>> a[6:0:-2] ['lobster', 'tomato', 'egg'] >>> a ['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster'] >>> a[::-1] ['lobster', 'ham', 'tomato', 'bacon', 'egg', 'spam'] ``` ### 删除 ```python >>> li = ['bread', 'butter', 'milk'] >>> li.pop() 'milk' >>> li ['bread', 'butter'] >>> del li[0] >>> li ['butter'] ``` ### 列表边界 ```python >>> li = ['a', 'b', 'c', 'd'] >>> li[0] 'a' >>> li[-1] 'd' >>> li[4] Traceback (most recent call last): File "", line 1, in IndexError: list index out of range ``` ### 连接 ```python >>> odd = [1, 3, 5] >>> odd.extend([9, 11, 13]) >>> odd [1, 3, 5, 9, 11, 13] >>> odd = [1, 3, 5] >>> odd + [9, 11, 13] [1, 3, 5, 9, 11, 13] ``` ### 排序和反转 ```python >>> li = [3, 1, 3, 2, 5] >>> li.sort() >>> li [1, 2, 3, 3, 5] >>> li.reverse() >>> li [5, 3, 3, 2, 1] ``` ### 计数 ```python >>> li = [3, 1, 3, 2, 5] >>> li.count(3) 2 ``` ### 重复 ```python >>> li = ["re"] * 3 >>> li ['re', 're', 're'] ``` Python 判断 ------------ ### 一般形式 ```python num = 5 if num > 10: print("num is totally bigger than 10.") elif num < 10: print("num is smaller than 10.") else: print("num is indeed 10.") ``` ### 单行形式 ```python >>> a = 330 >>> b = 200 >>> r = "a" if a > b else "b" >>> print(r) a ``` 注意条件是放在中间的 Python 循环 -------- ### 一般形式 ```python primes = [2, 3, 5, 7] for prime in primes: print(prime) ``` ### 带索引 ```python animals = ["dog", "cat", "mouse"] for i, value in enumerate(animals): print(i, value) ``` ### while 循环 ```python x = 0 while x < 4: print(x) x += 1 # Shorthand for x = x + 1 ``` ### 跳出循环 ```python x = 0 for index in range(10): x = index * 10 if index == 5: break print(x) ``` ### 跳过一轮循环 ```python for index in range(3, 8): x = index * 10 if index == 5: continue print(x) ``` ### 范围循环 ```python for i in range(4): print(i) # Prints: 0 1 2 3 for i in range(4, 8): print(i) # Prints: 4 5 6 7 for i in range(4, 10, 2): print(i) # Prints: 4 6 8 ``` ### 使用 zip() ```python name = ['Pete', 'John', 'Elizabeth'] age = [6, 23, 44] for n, a in zip(name, age): print('%s is %d years old' %(n, a)) ``` ### 列表生成式 ```python result = [x**2 for x in range(10) if x % 2 == 0] print(result) # [0, 4, 16, 36, 64] ``` Python 函数 -------- ### 基础 ```python def hello_world(): print('Hello, World!') ``` ### 返回 ```python {3} def add(x, y): print("x is %s, y is %s" %(x, y)) return x + y add(5, 6) # => 11 ``` ### 位置参数 ```python def varargs(*args): return args varargs(1, 2, 3) # => (1, 2, 3) ``` args 的类型是 tuple ### 关键字参数 ```python def keyword_args(**kwargs): return kwargs # => {"big": "foot", "loch": "ness"} keyword_args(big="foot", loch="ness") ``` kwargs 的类型是 dict ### 返回多个 ```python def swap(x, y): return y, x x = 1 y = 2 x, y = swap(x, y) # => x = 2, y = 1 ``` ### 默认值 ```python def add(x, y=10): return x + y add(5) # => 15 add(5, 20) # => 25 ``` ### 匿名函数 ```python # => True (lambda x: x > 2)(3) # => 5 (lambda x, y: x ** 2 + y ** 2)(2, 1) ``` Python 模块 -------- ### 导入模块 ```python import math print(math.sqrt(16)) # => 4.0 ``` ### 从一个模块导入 ```python from math import ceil, floor print(ceil(3.7)) # => 4.0 print(floor(3.7)) # => 3.0 ``` ### 导入一个模块的全部 ```python from math import * ``` ### 给模块起别名 ```python import math as m # => True math.sqrt(16) == m.sqrt(16) ``` ### 浏览模块的函数和属性 ```python import math dir(math) ``` Python 文件处理 ---------- ### 读取文件 #### 逐行 ```python with open("myfile.txt") as file: for line in file: print(line) ``` #### 带行号 ```python file = open('myfile.txt', 'r') for i, line in enumerate(file, start=1): print("Number %s: %s" % (i, line)) ``` ### 字符串 #### 写入一个字符串 ```python contents = {"aa": 12, "bb": 21} with open("myfile1.txt", "w+") as file: file.write(str(contents)) ``` #### 读取一个字符串 ```python with open('myfile1.txt', "r+") as file: contents = file.read() print(contents) ``` ### 对象 #### 写一个对象 ```python contents = {"aa": 12, "bb": 21} with open("myfile2.txt", "w+") as file: file.write(json.dumps(contents)) ``` #### 读取对象 ```python with open('myfile2.txt', "r+") as file: contents = json.load(file) print(contents) ``` ### 删除文件 ```python import os os.remove("myfile.txt") ``` ### 检查和删除 ```python import os if os.path.exists("myfile.txt"): os.remove("myfile.txt") else: print("The file does not exist") ``` ### 删除文件夹 ```python import os os.rmdir("myfolder") ``` Python 类和继承 -------- ### 定义 ```python class MyNewClass: pass # 类的实例化 my = MyNewClass() ``` ### 构造函数 ```python class Animal: def __init__(self, voice): self.voice = voice cat = Animal('Meow') print(cat.voice) # => Meow dog = Animal('Woof') print(dog.voice) # => Woof ``` ### 方法 ```python class Dog: # 类的方法 def bark(self): print("Ham-Ham") charlie = Dog() charlie.bark() # => "Ham-Ham" ``` ### 类变量 ```python class MyClass: class_variable = "A class variable!" # => 一个类变量！ print(MyClass.class_variable) x = MyClass() # => 一个类变量！ print(x.class_variable) ``` ### super() 函数 ```python class ParentClass: def print_test(self): print("Parent Method") class ChildClass(ParentClass): def print_test(self): print("Child Method") # 调用父级的 print_test() super().print_test() ``` --- ```python >>> child_instance = ChildClass() >>> child_instance.print_test() Child Method Parent Method ``` ### repr() 方法 ```python class Employee: def __init__(self, name): self.name = name def __repr__(self): return self.name john = Employee('John') print(john) # => John ``` ### 用户定义的异常 ```python class CustomError(Exception): pass ``` ### 多态性 ```python class ParentClass: def print_self(self): print('A') class ChildClass(ParentClass): def print_self(self): print('B') obj_A = ParentClass() obj_B = ChildClass() obj_A.print_self() # => A obj_B.print_self() # => B ``` ### 重写 ```python class ParentClass: def print_self(self): print("Parent") class ChildClass(ParentClass): def print_self(self): print("Child") child_instance = ChildClass() child_instance.print_self() # => Child ``` ### 继承 ```python class Animal: def __init__(self, name, legs): self.name = name self.legs = legs class Dog(Animal): def sound(self): print("Woof!") Yoki = Dog("Yoki", 4) print(Yoki.name) # => YOKI print(Yoki.legs) # => 4 Yoki.sound() # => Woof! ``` Python 类型标注 (Python 3.5+) -------- ### 变量 ```python string: str = "ha" times: int = 3 print(string * times) # => hahaha ``` ### 变量 ```python result: int = 1 + 2 print(result) # => 3 ``` 虽然标注了错误的类型，但不影响正常运行 ### 参数 ```python def say(name: str, start: str = "Hi"): return start + ", " + name print(say("Python")) # => Hi, Python ``` ### 位置参数 ```python def calc_summary(*args: int): return sum(args) print(calc_summary(3, 1, 4)) # => 8 ``` 表示 args 的所有元素都是 int 类型的。 ### 返回值 ```python def say_hello(name) -> str: return "Hello, " + name var = "Python" print(say_hello(var)) # => Hello, Python ``` ### 多种可能的返回值 ```python from typing import Union def resp200(meaningful) -> Union[int, str]: return "OK" if meaningful else 200 ``` 表示返回值可能是 int，也可能是 str 。 ### 关键字参数 ```python def calc_summary(**kwargs: int): return sum(kwargs.values()) print(calc_summary(a=1, b=2)) # => 3 ``` 表示 kwargs 的所有值都是 int 类型的。 ### 多个返回值 ```python def resp200() -> (int, str): return 200, "OK" ``` ### 多种可能的返回值 (3.10+) ```python def resp200(meaningful) -> int | str: return "OK" if meaningful else 200 ``` 自 Python 3.10 起可用。 ### 属性 ```python class Employee: name: str age: int def __init__(self, name, age): self.name = name self.age = age self.graduated: bool = False ``` ### 标注自己 ```python class Employee: name: str age: int def set_name(self, name) -> "Employee": self.name = name return self ``` 这里表示 set_name() 返回了一个 Employee 对象。 ### 标注自己 (3.11+) ```python from typing import Self class Employee: name: str age: int def set_name(self: Self, name) -> Self: self.name = name return self ``` ### 标注一个值为类型的参数 ```python from typing import TypeVar, Type T = TypeVar("T") # "mapper" 的值是一个像 int、str、MyClass 这样的类型 # "default" 是一个 T 类型的值，比如 314、"string"、MyClass() # 函数的返回值也是一个 T 类型的值 def converter(raw, mapper: Type[T], default: T) -> T: try: return mapper(raw) except: return default raw: str = input("请输入一个整数：") result: int = converter(raw, mapper=int, default=0) ``` ### 标注一个值为函数的参数 ```python from typing import TypeVar, Callable, Any T = TypeVar("T") def converter(raw, mapper: Callable[[Any], T], default: T) -> T: try: return mapper(raw) except: return default # Callable[[Any], T] 表示值是一个像这样声明的函数: # def anynomous(arg: Any) -> T: # pass def is_success(value) -> bool: return value in (0, "OK", True, "success") resp = dict(code=0, message="OK", data=[]) successed: bool = converter(resp.message, mapper=is_success, default=False) ``` 各种各样的 ---------- ### 注释 ```python # 这是单行注释 ``` --- ```python """ 可以写多行字符串 使用三个"，并且经常使用 作为文档。 """ ``` --- ```python ''' 可以写多行字符串 使用三个'，并且经常使用 作为文档。 ''' ``` ### 生成器 ```python def double_numbers(iterable): for i in iterable: yield i + i ``` 生成器可帮助您编写惰性代码 ### 要列出的生成器 ```python values = (-x for x in [1,2,3,4,5]) gen_to_list = list(values) # => [-1, -2, -3, -4, -5] print(gen_to_list) ``` ### 处理异常 ```python try: # 使用“raise”来引发错误 raise IndexError("这是一个索引错误") except IndexError as e: pass # pass只是一个空操作。 通常你会在这里做恢复。 except (TypeError, NameError): pass # 如果需要，可以一起处理多个异常。 else: # try/except 块的可选子句。 必须遵循除块之外的所有内容 print("All good!") # 仅当 try 中的代码未引发异常时运行 finally: # 在所有情况下执行 print("我们可以在这里清理资源") ``` 另见 ---- - [Python 官方网站](https://www.python.org/) _(python.org)_ - [Python 文档](https://docs.python.org/zh-cn/3/index.html) _(docs.python.org)_ - [Y 分钟学会 Python](https://learnxinyminutes.com/docs/zh-cn/python-cn/) _(learnxinyminutes.com)_ - [Python 中的正则表达式](./regex.md#python-中的正则表达式) _(jaywcjlove.github.io)_