07 - '笨方法'学Python¶

# 练习1: 打印"Hello, World!"
print("Hello, World!")

# 练习2: 变量和运算
x = 10
y = 20
z = x + y
print(f"{x} + {y} = {z}")

# 练习3: 条件判断
age = 18
if age >= 18:
    print("成年人")
else:
    print("未成年人")

# 练习4: 循环
for i in range(5):
    print(f"第{i+1}次循环")

# 练习5: 函数定义
def greet(name):
    return f"你好，{name}！"

# 练习6: 列表操作
numbers = [1, 2, 3, 4, 5]
squared = [x**2 for x in numbers]  # 列表推导式，简洁地从可迭代对象创建新列表
print(squared)

# 练习7: 字典操作
person = {
    "name": "张三",
    "age": 25,
    "city": "北京"
}
print(person["name"])

# 练习8: 类定义
class Dog:
    def __init__(self, name):
        self.name = name

    def bark(self):
        return f"{self.name}汪汪叫！"

dog = Dog("旺财")
print(dog.bark())

# 案例1: 斐波那契数列
def fibonacci(n):
    if n <= 1:
        return n
    return fibonacci(n-1) + fibonacci(n-2)

# 案例2: 阶乘计算
def factorial(n):
    if n == 0:
        return 1
    return n * factorial(n-1)

# 案例3: 判断素数
def is_prime(n):
    if n < 2:
        return False
    for i in range(2, int(n**0.5) + 1):
        if n % i == 0:
            return False
    return True

# 实用1: 文件读取
def read_file(filename):
    with open(filename, 'r', encoding='utf-8') as f:
        return f.read()

# 实用2: 文件写入
def write_file(filename, content):
    with open(filename, 'w', encoding='utf-8') as f:
        f.write(content)

# 实用3: 数据处理
def process_data(data):
    return [x * 2 for x in data]

# 实用4: 简单的Web请求
# 安装依赖: pip install requests
import requests

def fetch_url(url):
    response = requests.get(url)
    return response.text