KIOSHIROI's CS-learning Road

# 示例代码
try:
    x = int(input("请输入一个数字: "))
    y = 10 / x
    print(f"10 除以 {x} 的结果是 {y}")
except ZeroDivisionError:
    print("除零错误！不能用零作为除数。")
except ValueError:
    print("输入错误！请输入一个有效的数字。")

# 示例代码
try:
    x = int(input("请输入一个数字: "))
    y = 10 / x
except ZeroDivisionError:
    print("除零错误！不能用零作为除数。")
except ValueError:
    print("输入错误！请输入一个有效的数字。")
else:
    print(f"10 除以 {x} 的结果是 {y}")
finally:
    print("执行结束。")

# 自定义异常类
class NegativeNumberError(Exception):
    pass

def check_positive(number):
    if number < 0:
        raise NegativeNumberError("数字不能为负数！")

# 使用自定义异常
try:
    num = int(input("请输入一个正数: "))
    check_positive(num)
except NegativeNumberError as e:
    print(e)

# 示例代码
try:
    x = int(input("请输入一个数字: "))
    y = 10 / x
except Exception as e:
    print(f"发生异常: {e}")

# 示例代码
def divide_numbers(a, b):
    assert b != 0, "除数不能为零"
    return a / b

# 使用示例
try:
    result = divide_numbers(10, 0)
except AssertionError as e:
    print(f"断言错误：{e}")

# 基本用法
def check_age(age):
    if age < 0:
        raise ValueError("年龄不能为负数")
    if age > 150:
        raise ValueError("年龄不能超过150岁")
    return True

# 重新抛出异常
def process_age():
    try:
        age = int(input("请输入年龄："))
        check_age(age)
    except ValueError as e:
        print("处理异常...")
        raise  # 重新抛出当前异常

def convert_to_int(text):
    try:
        return int(text)
    except ValueError as e:
        raise ValueError("输入必须是数字") from e

# 使用示例
try:
    number = convert_to_int("abc")
except ValueError as e:
    print(f"错误：{e}")
    print(f"原始错误：{e.__cause__}")

# mymodule.py
def greet(name):
    return f"Hello, {name}!"

# main.py
import mymodule

print(mymodule.greet("Alice"))  # 输出 "Hello, Alice!"

# main.py
from mymodule import greet

print(greet("Bob"))  # 输出 "Hello, Bob!"

# module1.py
def add(a, b):
    return a + b

# module2.py
def subtract(a, b):
    return a - b

# main.py
from mypackage import module1, module2

print(module1.add(5, 3))        # 输出 8
print(module2.subtract(5, 3))   # 输出 2

import math

print(math.sqrt(16))  # 输出 4.0

import requests

response = requests.get("https://api.github.com")
print(response.status_code)  # 输出 200

# 创建字符串
str1 = 'Hello'
str2 = "World"
str3 = '''This is
a multiline
string'''

print(str1)  # 输出 Hello
print(str2)  # 输出 World
print(str3)  # 输出 This is\n a multiline\n string

# 字符串拼接
greeting = str1 + ' ' + str2
print(greeting)  # 输出 Hello World

# 字符串重复
repeat_str = str1 * 3
print(repeat_str)  # 输出 HelloHelloHello

name = "Alice"
age = 25

# 百分号格式化
print("Hello, %s. You are %d years old." % (name, age))

# str.format()方法
print("Hello, {}. You are {} years old.".format(name, age))

# f字符串（Python 3.6及以上）
print(f"Hello, {name}. You are {age} years old.")

# 字符串索引
s = "Python"
print(s[0])  # 输出 P
print(s[-1])  # 输出 n

# 字符串切片
print(s[1:4])  # 输出 yth
print(s[:3])  # 输出 Pyt
print(s[3:])  # 输出 hon

s = "hello, world"

# 大小写转换
print(s.upper())  # 输出 HELLO, WORLD
print(s.lower())  # 输出 hello, world
print(s.capitalize())  # 输出 Hello, world
print(s.title())  # 输出 Hello, World

# 去除空白字符
s2 = "  hello  "
print(s2.strip())  # 输出 hello
print(s2.lstrip())  # 输出 hello  
print(s2.rstrip())  # 输出   hello

# 查找和替换
print(s.find("world"))  # 输出 7
print(s.replace("world", "Python"))  # 输出 hello, Python

# 拆分和连接
words = s.split(", ")
print(words)  # 输出 ['hello', 'world']
print(", ".join(words))  # 输出 hello, world

s = "hello"
# s[0] = 'y' 错误！
s = s.replace("h", "y")
print(s)  # 输出 yello

# 编码
s = "hello"
b = s.encode("utf-8")
print(b)  # 输出 b'hello'

# 解码
s2 = b.decode("utf-8")
print(s2)  # 输出 hello

# 多行字符串
multi_line_str = """This is a
multiline
string"""
print(multi_line_str)

# 转义字符
escaped_str = "He said, \"Hello!\""
print(escaped_str)  # 输出 He said, "Hello!"

# 打开文件
file = open("example.txt", "r")

# 读取文件内容
content = file.read()
print(content)

# 关闭文件
file.close()

# 使用 with 语句打开文件
with open("example.txt", "r") as file:
    content = file.read()
    print(content)

# 读取整个文件
with open("example.txt", "r") as file:
    content = file.read()
    print(content)

# 逐行读取文件
with open("example.txt", "r") as file:
    for line in file:
        print(line.strip())

# 读取一行
with open("example.txt", "r") as file:
    line = file.readline()
    print(line)

# 读取所有行并返回列表
with open("example.txt", "r") as file:
    lines = file.readlines()
    print(lines)

# 写入文件
with open("example.txt", "w") as file:
    file.write("Hello, World!\n")
    file.write("This is a new line.\n")

# 写入多行
lines = ["First line.\n", "Second line.\n", "Third line.\n"]
with open("example.txt", "w") as file:
    file.writelines(lines)

# 以追加模式打开文件
with open("example.txt", "a") as file:
    file.write("This line is appended.\n")

# 以二进制模式读取文件
with open("example.jpg", "rb") as file:
    content = file.read()
    print(content)

import os

# 检查文件是否存在
print(os.path.exists("example.txt"))

# 获取文件大小
print(os.path.getsize("example.txt"))

# 重命名文件
os.rename("example.txt", "new_example.txt")

# 删除文件
os.remove("new_example.txt")

# 创建目录
os.mkdir("example_dir")

# 删除目录
os.rmdir("example_dir")