# 这是一个注释

'''这是多行注释'''
"""
这也是多行注释
"""

x = 10  # 整数 
y = 3.14  # 浮动数 
name = "John"  # 字符串 
is_active = True  # 布尔值

my_list = [1, 2, 3, 4]

my_tuple = (1, 2, 3)

my_dict = {"name": "John", "age": 30}

my_set = {1, 2, 3}

if x > 0:
    print("x是正数")
elif x == 0:
    print("x是零")
else:
    print("x是负数")

for i in range(5):
    print(i)

count = 0
while count < 5:
    print(count)
    count += 1

def greet(name):
    return f"Hello, {name}!"

print(greet("Alice"))

try:
    x = 1 / 0
except ZeroDivisionError:
    print("不能除以零")

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def greet(self):
        print(f"Hello, my name is {self.name} and I am {self.age} years old.")

person = Person("John", 30)
person.greet()

import math
print(math.sqrt(16))  # 4.0

from math import sqrt
print(sqrt(16))  # 4.0

squares = [x ** 2 for x in range(5)]
print(squares)  # [0, 1, 4, 9, 16]

add = lambda x, y: x + y
print(add(2, 3))  # 5

with open('file.txt', 'r') as file:
    content = file.read()
    print(content)

with open('file.txt', 'w') as file:
    file.write("Hello, World!")

list1 = [1, 2]
list2 = [3, 4]
combined = list1 + list2
print(combined)  # [1, 2, 3, 4]

repeated = [1, 2] * 3
print(repeated)  # [1, 2, 1, 2, 1, 2]

nums = [1, 2, 3]
iter_nums = iter(nums)
print(next(iter_nums))  # 1
print(next(iter_nums))  # 2

def count_up_to(max):
    count = 1
    while count <= max:
        yield count
        count += 1

name = "Alice"
age = 30
print(f"My name is {name} and I am {age} years old.")

from enum import Enum

class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3

x = 10          # 整数
name = "Alice"  # 字符串
is_valid = True # 布尔值

a, b, c = 1, 2, "hello"
print(a, b, c)  # 输出: 1 2 hello

x = y = z = 0
print(x, y, z)  # 输出: 0 0 0

a = [1, 2, 3]  # 列表
b = a           # b 指向与 a 相同的列表
b.append(4)
print(a)        # 输出: [1, 2, 3, 4]

x = 10
y = 3
print(x + y)  # 加法: 13
print(x - y)  # 减法: 7
print(x * y)  # 乘法: 30
print(x / y)  # 除法: 3.333...
print(x // y) # 整除: 3
print(x % y)  # 取余: 1
print(x ** y) # 幂: 1000

a = 5.5
b = 2.2
print(round(a + b, 2))  # 输出: 7.7

z = 2 + 3j
print(z.real, z.imag)  # 输出: 2.0 3.0

s = "hello"
print(len(s))          # 长度: 5
print(s.upper())       # 转大写: HELLO
print(s.lower())       # 转小写: hello
print(s.capitalize())  # 首字母大写: Hello
print(s * 3)           # 重复: hellohellohello

s = "Python"
print(s[0])       # 输出: P
print(s[-1])      # 输出: n
print(s[1:4])     # 输出: yth

name = "Alice"
age = 25
print(f"My name is {name}, and I am {age} years old.")

print(5 > 3)  # 输出: True
print(bool(0))  # 输出: False
print(bool("Non-empty"))  # 输出: True

lst = [1, 2, 3, "hello"]
print(lst[0])  # 输出: 1
print(lst[-1]) # 输出: hello

lst.append(4)      # 添加元素
lst.insert(1, 10)  # 插入元素
lst.remove(10)     # 删除指定值
lst.pop()          # 弹出最后一个值
lst.sort()         # 排序

t = (1, 2, 3)
print(t[0])  # 输出: 1

d = {"name": "Alice", "age": 25}
print(d["name"])  # 输出: Alice

d["age"] = 26       # 修改值
d["gender"] = "F"   # 添加键值对
del d["gender"]     # 删除键值对

s = {1, 2, 3}
s.add(4)  # 添加元素
s.remove(2)  # 删除元素

x = "123"
print(int(x))  # 转换为整数: 123
print(float(x))  # 转换为浮点数: 123.0
print(list(x))  # 转换为列表: ['1', '2', '3']
print(tuple(x)) # 转换为元组: ('1', '2', '3')
print(set(x))   # 转换为集合: {'1', '3', '2'}

x = 10
print(type(x))  # 输出: <class 'int'>

my_string.upper()     # 全部转为大写
my_string.lower()     # 全部转为小写
my_string.capitalize()  # 整个字符串的首字母大写，其余字母小写
my_string.title() #将字符串中的每个单词的首字母大写，其余字母小写

my_string.strip()     # 去除两端的空白字符
my_string.lstrip()    # 去除左侧空白字符
my_string.rstrip()    # 去除右侧空白字符

parts = my_string.split(",")    # 按逗号分割字符串
joined = " ".join(parts)        # 用空格连接多个字符串

new_string = my_string.replace("world", "Python")  # 替换子字符串

nostarch_url = 'https://nostarch.com' #删除URL前缀 https://
nostarch_url.removeprefix('https://') 
# 输出'nostarch.com'

formatted = "Hello, %s!" % "world"

formatted = "Hello, {}!".format("world")

name = "world"
formatted = f"Hello, {name}!"

my_string = "Hello, world!"
substring = my_string[0:5]   # 获取前5个字符 "Hello"
reversed_string = my_string[::-1]  # 反转字符串

position = my_string.find("world")  # 返回子字符串的位置
exists = "world" in my_string       # 检查是否存在

count = my_string.count("l")  # 统计字符 'l' 出现的次数

is_alpha = my_string.isalpha()   # 是否全是字母
is_digit = my_string.isdigit()   # 是否全是数字
is_space = my_string.isspace()   # 是否全是空白字符

multi_line = """This is a
multi-line string."""

encoded = my_string.encode("utf-8")  # 编码为字节
decoded = encoded.decode("utf-8")   # 从字节解码回字符串

part1 = "Hello"
part2 = "world"
combined = part1 + ", " + part2 + "!"

my_list = []
my_list = list()  # 等价于上面

my_list = [1, 2, 3, 4]
my_list = ["apple", "banana", "cherry"]

my_list = [1, "hello", 3.14, [1, 2, 3]]

my_list = [10, 20, 30, 40, 50]
print(my_list[0])  # 10，正向索引从 0 开始
print(my_list[-1])  # 50，反向索引从 -1 开始

print(my_list[1:4])  # [20, 30, 40]，不包含结束索引
print(my_list[:3])   # [10, 20, 30]，省略起始默认为 0
print(my_list[2:])   # [30, 40, 50]，省略结束默认为最后
print(my_list[::2])  # [10, 30, 50]，步长为 2

my_list = [1, 2, 3]
my_list[1] = 20
print(my_list)  # [1, 20, 3]

my_list[1:3] = [200, 300]
print(my_list)  # [1, 200, 300]

my_list = [1, 2, 3]
my_list.append(4)
print(my_list)  # [1, 2, 3, 4]

my_list = [1, 2, 3]
my_list.insert(1, 100)
print(my_list)  # [1, 100, 2, 3]

my_list = [1, 2, 3]
my_list.extend([4, 5, 6])
print(my_list)  # [1, 2, 3, 4, 5, 6]

my_list = [1, 2, 3, 2]
my_list.remove(2)
print(my_list)  # [1, 3, 2]

my_list = [1, 2, 3]
value = my_list.pop(1)
print(value)  # 2
print(my_list)  # [1, 3]

my_list = [1, 2, 3, 4]
del my_list[1]
print(my_list)  # [1, 3, 4]
del my_list[1:3]
print(my_list)  # [1]

my_list = [1, 2, 3]
my_list.clear()
print(my_list)  # []

my_list = [10, 20, 30]
print(my_list.index(20))  # 1

my_list = [1, 2, 2, 3]
print(my_list.count(2))  # 2

my_list = [3, 1, 2]
my_list.sort()
print(my_list)  # [1, 2, 3]

my_list.sort(reverse=True)
print(my_list)  # [3, 2, 1]

my_list = [1, 2, 3]
my_list.reverse()
print(my_list)  # [3, 2, 1]

my_list = [3, 1, 2]
new_list = sorted(my_list)
print(new_list)  # [1, 2, 3]
print(my_list)  # [3, 1, 2]

my_list = [1, 2, 3]
print(len(my_list))  # 3

my_list = [1, 2, 3]
print(max(my_list))  # 3
print(min(my_list))  # 1

my_list = [1, 2, 3]
print(2 in my_list)  # True
print(4 not in my_list)  # True

my_list = [1, 2, 3]
copy_list = my_list.copy()
print(copy_list)  # [1, 2, 3]

squares = [x**2 for x in range(5)]
print(squares)  # [0, 1, 4, 9, 16]

matrix = [[1, 2], [3, 4]]
print(matrix[0][1])  # 2

list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
combined = list(zip(list1, list2))
print(combined)  # [(1, 'a'), (2, 'b'), (3, 'c')]

my_tuple = ()
my_tuple = tuple()  # 等价于上面

my_tuple = (1, 2, 3)
my_tuple = ("apple", "banana", "cherry")

single_tuple = (1,)  # 正确
not_a_tuple = (1)    # 错误，类型为 int

my_tuple = (1, "hello", 3.14, [1, 2, 3])

my_tuple = tuple([1, 2, 3])  # 将列表转为元组
print(my_tuple)  # (1, 2, 3)

my_tuple = (10, 20, 30, 40, 50)
print(my_tuple[0])  # 10，正向索引从 0 开始
print(my_tuple[-1])  # 50，反向索引从 -1 开始

print(my_tuple[1:4])  # (20, 30, 40)，不包含结束索引
print(my_tuple[:3])   # (10, 20, 30)
print(my_tuple[2:])   # (30, 40, 50)
print(my_tuple[::2])  # (10, 30, 50)，步长为 2

my_tuple = (1, 2, 3)
my_tuple[1] = 100  # 抛出 TypeError

del my_tuple[1]  # 抛出 TypeError

my_tuple = (1, [2, 3], 4)
my_tuple[1][0] = 200
print(my_tuple)  # (1, [200, 3], 4)

tuple1 = (1, 2)
tuple2 = (3, 4)
combined = tuple1 + tuple2
print(combined)  # (1, 2, 3, 4)

my_tuple = (1, 2)
repeated = my_tuple * 3
print(repeated)  # (1, 2, 1, 2, 1, 2)

my_tuple = (1, 2, 3)
print(2 in my_tuple)  # True
print(4 not in my_tuple)  # True

my_tuple = (1, 2, 2, 3)
print(my_tuple.count(2))  # 2

my_tuple = (10, 20, 30, 20)
print(my_tuple.index(20))  # 1

my_tuple = (1, 2, 3)
a, b, c = my_tuple
print(a, b, c)  # 1 2 3

my_tuple = (1, 2, 3, 4)
a, *b, c = my_tuple
print(a)  # 1
print(b)  # [2, 3]
print(c)  # 4

my_tuple = (10, 20, 30)
for item in my_tuple:
    print(item)

my_tuple = (3, 1, 2)
sorted_list = sorted(my_tuple)
print(sorted_list)  # [1, 2, 3]

my_tuple = (1, 2, 3)
my_list = list(my_tuple)  # 转为列表
new_tuple = tuple(my_list)  # 再转为元组

nested_tuple = ((1, 2), (3, 4))
print(nested_tuple[1][0])  # 3

my_dict = {(1, 2): "value"}
print(my_dict[(1, 2)])  # value

def get_coordinates():
    return (10, 20)

x, y = get_coordinates()
print(x, y)  # 10 20

my_dict = {}
my_dict = dict()

# 直接赋值
my_dict = {"name": "Alice", "age": 25, "city": "New York"}

# 使用 dict() 函数
my_dict = dict(name="Alice", age=25, city="New York")

# 使用元组列表
my_dict = dict([("name", "Alice"), ("age", 25), ("city", "New York")])

# 使用字典推导式
keys = ["name", "age", "city"]
values = ["Alice", 25, "New York"]
my_dict = {k: v for k, v in zip(keys, values)}

my_dict = {"name": "Alice", "age": 25}
print(my_dict["name"])  # Alice

print(my_dict.get("name"))      # Alice
print(my_dict.get("gender"))    # None
print(my_dict.get("gender", "Not Specified"))  # Not Specified

my_dict["age"] = 30  # 更新键值对
my_dict["gender"] = "Female"  # 添加新键值对
print(my_dict)  # {'name': 'Alice', 'age': 30, 'gender': 'Female'}

my_dict.update({"age": 35, "city": "London"})
print(my_dict)  # {'name': 'Alice', 'age': 35, 'gender': 'Female', 'city': 'London'}

del my_dict["age"]
print(my_dict)  # {'name': 'Alice', 'gender': 'Female'}

removed_value = my_dict.pop("gender")
print(removed_value)  # Female
print(my_dict)  # {'name': 'Alice'}

last_item = my_dict.popitem()
print(last_item)  # ('city', 'London')

my_dict.clear()
print(my_dict)  # {}

for key in my_dict:
    print(key)

for value in my_dict.values():
    print(value)

for key, value in my_dict.items():
    print(f"{key}: {value}")

keys = my_dict.keys()      # dict_keys(['name', 'age', 'city'])
values = my_dict.values()  # dict_values(['Alice', 25, 'New York'])
items = my_dict.items()    # dict_items([('name', 'Alice'), ('age', 25), ('city', 'New York')])

print("name" in my_dict)  # True
print("gender" not in my_dict)  # True

new_dict = dict.fromkeys(["a", "b", "c"], 0)
print(new_dict)  # {'a': 0, 'b': 0, 'c': 0}

value = my_dict.setdefault("gender", "Female")
print(value)  # Female
print(my_dict)  # {'name': 'Alice', 'age': 25, 'city': 'New York', 'gender': 'Female'}

dict1 = {"a": 1, "b": 2}
dict2 = {"b": 3, "c": 4}
dict1.update(dict2)
print(dict1)  # {'a': 1, 'b': 3, 'c': 4}

dict1 = {"a": 1, "b": 2}
dict2 = {"b": 3, "c": 4}
new_dict = dict1 | dict2
print(new_dict)  # {'a': 1, 'b': 3, 'c': 4}

squares = {x: x**2 for x in range(5)}
print(squares)  # {0: 0, 1: 1, 2: 4, 3: 9, 4: 16}

from collections import Counter
text = "hello world"
frequency = Counter(text)
print(frequency)  # Counter({'l': 3, 'o': 2, 'h': 1, 'e': 1, ' ': 1, 'w': 1, 'r': 1, 'd': 1})

my_dict = {[1, 2]: "value"}  # TypeError: unhashable type: 'list'

my_dict = {"a": 1, "a": 2}
print(my_dict)  # {'a': 2}

sorted_dict = dict(sorted(my_dict.items()))

sorted_dict = dict(sorted(my_dict.items(), key=lambda item: item[1]))

import copy
deep_copy_dict = copy.deepcopy(my_dict)

x = 10
if x > 0:
    print("Positive")
elif x == 0:
    print("Zero")
else:
    print("Negative")

x = 10
print("Positive") if x > 0 else print("Negative or Zero")

x = 10
if x > 0:
    if x % 2 == 0:
        print("Positive and Even")
    else:
        print("Positive and Odd")

# 遍历列表
for item in [1, 2, 3]:
    print(item)

# 遍历字符串
for char in "hello":
    print(char)

# 遍历字典
my_dict = {"name": "Alice", "age": 25}
for key, value in my_dict.items():
    print(f"{key}: {value}")

x = 0
while x < 5:
    print(x)
    x += 1

for i in range(5):
    if i == 3:
        break
    print(i)  # 输出 0, 1, 2

for i in range(5):
    if i == 3:
        continue
    print(i)  # 输出 0, 1, 2, 4

for i in range(5):
    if i == 3:
        break
else:
    print("Completed without break")  # 不执行

while False:
    pass
else:
    print("While loop completed")  # 执行

for i in range(5):       # 0, 1, 2, 3, 4
    print(i)

for i in range(1, 5):    # 1, 2, 3, 4
    print(i)

for i in range(1, 10, 2): # 1, 3, 5, 7, 9
    print(i)

my_list = ['a', 'b', 'c']
for index, value in enumerate(my_list):
    print(index, value)  # 输出 (0, 'a'), (1, 'b'), (2, 'c')

names = ["Alice", "Bob", "Charlie"]
ages = [25, 30, 35]
for name, age in zip(names, ages):
    print(name, age)  # 输出 ('Alice', 25), ('Bob', 30), ('Charlie', 35)

for i in reversed(range(5)):
    print(i)  # 输出 4, 3, 2, 1, 0

for i in sorted([3, 1, 2]):
    print(i)  # 输出 1, 2, 3

# 生成平方数列表
squares = [x**2 for x in range(5)]
print(squares)  # [0, 1, 4, 9, 16]

# 带条件的推导式
evens = [x for x in range(10) if x % 2 == 0]
print(evens)  # [0, 2, 4, 6, 8]

while True:
    x = input("Enter something: ")
    if x == "exit":
        break
    print(f"You entered {x}")

for i in range(3):
    for j in range(2):
        print(f"i={i}, j={j}")

for i in range(10):
    if i % 2 == 0:
        print(f"{i} is even")
    else:
        print(f"{i} is odd")

def greet(name):
    return f"Hello, {name}!"

print(greet("Alice"))  # 输出: Hello, Alice!

def add(a, b):
    return a + b
print(add(5, 3))  # 输出: 8

def greet(name, greeting="Hello"):
    return f"{greeting}, {name}!"
print(greet("Alice"))        # 输出: Hello, Alice!
print(greet("Alice", "Hi"))  # 输出: Hi, Alice!

def sum_numbers(*args):
    return sum(args)
print(sum_numbers(1, 2, 3, 4))  # 输出: 10

def print_info(**kwargs):
    for key, value in kwargs.items():
        print(f"{key}: {value}")
print_info(name="Alice", age=25)  
# 输出:
# name: Alice
# age: 25

def greet(name, *, greeting="Hello"):
    return f"{greeting}, {name}!"
print(greet("Alice", greeting="Hi"))  # 输出: Hi, Alice!

def greet(name, greeting):
    return f"{greeting}, {name}!"
args = ("Alice", "Hi")
print(greet(*args))  # 输出: Hi, Alice!

kwargs = {"name": "Alice", "greeting": "Hello"}
print(greet(**kwargs))  # 输出: Hello, Alice!

def square(x):
    return x ** 2
print(square(4))  # 输出: 16

def operations(a, b):
    return a + b, a - b, a * b, a / b
result = operations(10, 2)
print(result)         # 输出: (12, 8, 20, 5.0)
add, sub, mul, div = result
print(add, sub)       # 输出: 12, 8

x = 10  # 全局变量

def change_value():
    x = 20  # 局部变量
    print("Inside function:", x)

change_value()         # 输出: Inside function: 20
print("Outside function:", x)  # 输出: Outside function: 10

x = 10

def change_global():
    global x
    x = 20

change_global()
print(x)  # 输出: 20

def outer():
    x = 10
    def inner():
        nonlocal x
        x = 20
    inner()
    print(x)

outer()  # 输出: 20

square = lambda x: x ** 2
print(square(4))  # 输出: 16

add = lambda a, b: a + b
print(add(2, 3))  # 输出: 5

nums = [1, 2, 3, 4]
squared = map(lambda x: x ** 2, nums)
print(list(squared))  # 输出: [1, 4, 9, 16]

nums = [1, 2, 3, 4]
evens = filter(lambda x: x % 2 == 0, nums)
print(list(evens))  # 输出: [2, 4]

from functools import reduce
nums = [1, 2, 3, 4]
product = reduce(lambda x, y: x * y, nums)
print(product)  # 输出: 24

def my_decorator(func):
    def wrapper():
        print("Something before the function.")
        func()
        print("Something after the function.")
    return wrapper

@my_decorator
def say_hello():
    print("Hello!")

say_hello()
# 输出:
# Something before the function.
# Hello!
# Something after the function.

def greet(name):
    """
    Greets a person with the given name.

    Args:
        name (str): The name of the person.

    Returns:
        str: The greeting message.
    """
    return f"Hello, {name}!"

print(greet.__doc__)

class MyClass:
    pass  # 表示空类

obj = MyClass()
print(obj)  # 输出: <__main__.MyClass object at 0x...>

class MyClass:
    def __init__(self, name, age):
        self.name = name  # 实例属性
        self.age = age

# 创建对象
person = MyClass("Alice", 25)
print(person.name)  # 输出: Alice
print(person.age)   # 输出: 25

class MyClass:
    def __init__(self, name):
        self.name = name

    def greet(self):
        return f"Hello, {self.name}!"

person = MyClass("Alice")
print(person.greet())  # 输出: Hello, Alice!

class MyClass:
    species = "Human"  # 类属性

    def __init__(self, name):
        self.name = name

print(MyClass.species)  # 输出: Human
person = MyClass("Alice")
print(person.species)   # 输出: Human

class MyClass:
    species = "Human"

    @classmethod
    def set_species(cls, species):
        cls.species = species

MyClass.set_species("SuperHuman")
print(MyClass.species)  # 输出: SuperHuman

class MyClass:
    @staticmethod
    def add(a, b):
        return a + b

print(MyClass.add(2, 3))  # 输出: 5

class MyClass:
    def __init__(self, name):
        self.name = name

class MyClass:
    def __init__(self, name):
        self.name = name

    def __str__(self):
        return f"My name is {self.name}."

person = MyClass("Alice")
print(person)  # 输出: My name is Alice.

class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)

    def __str__(self):
        return f"({self.x}, {self.y})"

p1 = Point(1, 2)
p2 = Point(3, 4)
print(p1 + p2)  # 输出: (4, 6)

class Parent:
    def greet(self):
        return "Hello from Parent"

class Child(Parent):
    pass

child = Child()
print(child.greet())  # 输出: Hello from Parent

class Parent:
    def greet(self):
        return "Hello from Parent"

class Child(Parent):
    def greet(self):
        return "Hello from Child"

child = Child()
print(child.greet())  # 输出: Hello from Child

class A:
    def method_a(self):
        return "Method from A"

class B:
    def method_b(self):
        return "Method from B"

class C(A, B):
    pass

c = C()
print(c.method_a())  # 输出: Method from A
print(c.method_b())  # 输出: Method from B

class MyClass:
    def __init__(self, name):
        self.name = name  # 公有属性

obj = MyClass("Alice")
print(obj.name)  # 输出: Alice

class MyClass:
    def __init__(self, name):
        self.__name = name  # 私有属性

    def get_name(self):
        return self.__name

obj = MyClass("Alice")
print(obj.get_name())  # 输出: Alice

class MyClass:
    pass

obj = MyClass()
obj.name = "Alice"  # 动态添加属性
print(obj.name)     # 输出: Alice

class MyClass:
    def __init__(self, name):
        self.__name = name

    @property
    def name(self):
        return self.__name

    @name.setter
    def name(self, value):
        self.__name = value

person = MyClass("Alice")
print(person.name)  # 输出: Alice
person.name = "Bob"
print(person.name)  # 输出: Bob

class MyClass:
    __slots__ = ['name', 'age']

obj = MyClass()
obj.name = "Alice"
obj.age = 25
# obj.gender = "Female"  # 会报错

open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)

with open('example.txt', 'r', encoding='utf-8') as file:
    content = file.read()
    print(content)

with open('example.txt', 'r', encoding='utf-8') as file:
    # 一次读取一行
    line = file.readline()
    print(line)
    
    # 读取所有行
    lines = file.readlines()
    print(lines)

with open('example.txt', 'r', encoding='utf-8') as file:
    for line in file:
        print(line.strip())  # 去除末尾换行符

with open('example.txt', 'w', encoding='utf-8') as file:
    file.write("Hello, World!\n")
    file.write("Python file operations.\n")

lines = ["First line\n", "Second line\n", "Third line\n"]
with open('example.txt', 'w', encoding='utf-8') as file:
    file.writelines(lines)

with open('example.txt', 'a', encoding='utf-8') as file:
    file.write("This line is appended.\n")

with open('example.txt', 'r', encoding='utf-8') as file:
    print(file.tell())

with open('example.txt', 'r', encoding='utf-8') as file:
    file.seek(5)  # 将指针移动到第 5 个字节
    print(file.read())  # 从新位置开始读取

file = open('example.txt', 'r')
content = file.read()
file.close()  # 手动关闭文件

with open('example.txt', 'r') as file:
    content = file.read()
# 文件已自动关闭

import os

# 判断文件是否存在
print(os.path.exists('example.txt'))

# 删除文件
os.remove('example.txt')

# 重命名文件
os.rename('old_name.txt', 'new_name.txt')

import shutil

# 复制文件
shutil.copy('source.txt', 'destination.txt')

# 移动文件
shutil.move('source.txt', 'new_directory/')

# 读取二进制文件
with open('image.jpg', 'rb') as file:
    data = file.read()

# 写入二进制文件
with open('output.jpg', 'wb') as file:
    file.write(data)

try:
    with open('nonexistent.txt', 'r') as file:
        content = file.read()
except FileNotFoundError:
    print("File not found!")
except PermissionError:
    print("Permission denied!")

import tempfile

# 创建临时文件
with tempfile.TemporaryFile(mode='w+t') as temp_file:
    temp_file.write("Temporary data\n")
    temp_file.seek(0)
    print(temp_file.read())  # 输出: Temporary data

try:
    # 可能发生异常的代码
except:
    # 异常发生时执行的代码
else:
    # 没有异常时执行的代码
finally:
    # 无论是否发生异常，都会执行的代码

try:
    result = 10 / 0
except ZeroDivisionError:
    print("除数不能为零！")

try:
    x = int("abc")
except (ValueError, TypeError):
    print("发生值错误或类型错误！")

try:
    result = 10 / 0
except Exception as e:
    print(f"发生异常：{e}")

try:
    result = 10 / 2
except ZeroDivisionError:
    print("除数不能为零！")
else:
    print("计算成功，结果为：", result)

try:
    file = open("example.txt", "r")
except FileNotFoundError:
    print("文件未找到！")
finally:
    print("操作结束，无论是否发生异常。")

class CustomError(Exception):
    def __init__(self, message):
        self.message = message

try:
    raise CustomError("这是一个自定义异常！")
except CustomError as e:
    print(f"捕获自定义异常：{e.message}")