1
# 创建一个变量，存储名字
2
name = "张三"
3

4
# 创建一个变量，存储年龄
5
age = 25
6

7
# 打印变量的值
8
print(name)  # 输出：张三
9
print(age)   # 输出：25

1
# 字符串（文本）
2
text = "Hello, World!"
3

4
# 整数（整数）
5
number = 42
6

7
# 浮点数（小数）
8
price = 19.99
9

10
# 布尔值（真或假）
11
is_valid = True
12
is_valid = False
13

14
# 列表（多个数据）
15
fruits = ["苹果", "香蕉", "橙子"]
16

17
# 字典（键值对）
18
person = {
19
    "name": "张三",
20
    "age": 25,
21
    "city": "北京"
22
}

1
# 定义一个函数
2
def say_hello(name):
3
    print(f"你好，{name}！")
4

5
# 调用函数
6
say_hello("张三")  # 输出：你好，张三！
7
say_hello("李四")  # 输出：你好，李四！

1
age = 18
2

3
if age >= 18:
4
    print("成年人")
5
else:
6
    print("未成年人")

1
# for 循环
2
fruits = ["苹果", "香蕉", "橙子"]
3
for fruit in fruits:
4
    print(fruit)
5
# 输出：
6
# 苹果
7
# 香蕉
8
# 橙子

1
POST /api/chat HTTP/1.1
2
Host: api.example.com
3
Content-Type: application/json
4
Authorization: Bearer sk-xxxxx
5

6
{
7
  "message": "你好"
8
}

1
import requests
2

3
# API 地址
4
url = "https://api.example.com/api/chat"
5

6
# 请求头
7
headers = {
8
    "Content-Type": "application/json",
9
    "Authorization": "Bearer sk-xxxxx"
10
}
11

12
# 请求体
13
data = {
14
    "message": "你好"
15
}
16

17
# 发送 POST 请求
18
response = requests.post(url, headers=headers, json=data)
19

20
# 打印响应
21
print(response.json())

1
{
2
  "name": "张三",
3
  "age": 25,
4
  "city": "北京",
5
  "hobbies": ["读书", "游泳", "编程"],
6
  "address": {
7
    "street": "长安街",
8
    "number": 1
9
  }
10
}

1
import json
2

3
# 将 Python 对象转换为 JSON 字符串
4
data = {
5
    "name": "张三",
6
    "age": 25
7
}
8
json_string = json.dumps(data)
9
print(json_string)
10
# 输出：{"name": "张三", "age": 25}
11

12
# 将 JSON 字符串转换为 Python 对象
13
json_string = '{"name": "张三", "age": 25}'
14
data = json.loads(json_string)
15
print(data["name"])  # 输出：张三

1
# 示例 1：处理除以零的错误
2
try:
3
    result = 10 / 0
4
    print(result)
5
except ZeroDivisionError:
6
    print("错误：不能除以零！")
7

8
# 示例 2：处理列表索引越界
9
fruits = ["苹果", "香蕉", "橙子"]
10
try:
11
    print(fruits[10])  # 不存在的索引
12
except IndexError:
13
    print("错误：索引超出范围！")

1
try:
2
    # 可能会出错的代码
3
    result = int("abc")
4
except Exception as e:
5
    print(f"发生错误：{e}")

1
import requests
2

3
try:
4
    response = requests.get("https://api.example.com/data")
5
    response.raise_for_status()  # 如果状态码不是 200，抛出异常
6
    data = response.json()
7
    print(data)
8
except requests.exceptions.RequestException as e:
9
    print(f"请求失败：{e}")
10
except json.JSONDecodeError:
11
    print("响应不是有效的 JSON 格式")

1
try:
2
    file = open("data.txt", "r")
3
    content = file.read()
4
except FileNotFoundError:
5
    print("文件不存在")
6
finally:
7
    file.close()  # 确保文件被关闭

1
def calculate(a, b):
2
    print(f"输入：a={a}, b={b}")  # 调试输出
3
    result = a + b
4
    print(f"结果：{result}")  # 调试输出
5
    return result
6

7
calculate(10, 20)

1
Traceback (most recent call last):
2
  File "example.py", line 5, in <module>
3
    result = 10 / 0
4
ZeroDivisionError: division by zero

1
# 单行注释：解释这行代码的作用
2
name = "张三"
3

4
"""
5
多行注释：
6
用于解释复杂的功能或逻辑
7
"""
8
def calculate_discount(price, discount_rate):
9
    """
10
    计算折扣后的价格
11

12
    Args:
13
        price: 原价
14
        discount_rate: 折扣率（0-1）
15

16
    Returns:
17
        折扣后的价格
18
    """
19
    return price * (1 - discount_rate)

1
# ✅ 正确
2
if age >= 18:
3
    print("成年人")
4
    if has_id:
5
        print("可以进入")
6

7
# ❌ 错误（使用 Tab）
8
if age >= 18:
9
  print("成年人")

1
def calculator(a, b, operator):
2
    """
3
    简单计算器
4

5
    Args:
6
        a: 第一个数字
7
        b: 第二个数字
8
        operator: 运算符（+、-、*、/）
9

10
    Returns:
11
        计算结果
12
    """
13
    try:
14
        if operator == '+':
15
            return a + b
16
        elif operator == '-':
17
            return a - b
18
        elif operator == '*':
19
            return a * b
20
        elif operator == '/':
21
            if b == 0:
22
                return "错误：不能除以零"
23
            return a / b
24
        else:
25
            return "错误：不支持的运算符"
26
    except Exception as e:
27
        return f"错误：{e}"
28

29
# 测试
30
print(calculator(10, 5, '+'))  # 输出：15
31
print(calculator(10, 5, '/'))  # 输出：2.0
32
print(calculator(10, 0, '/'))  # 输出：错误：不能除以零

1
# 学生成绩字典
2
students = {
3
    "张三": {"语文": 85, "数学": 90, "英语": 88},
4
    "李四": {"语文": 78, "数学": 95, "英语": 82},
5
    "王五": {"语文": 92, "数学": 88, "英语": 90}
6
}
7

8
def calculate_average(scores):
9
    """计算平均分"""
10
    return sum(scores.values()) / len(scores)
11

12
def get_student_info(name):
13
    """获取学生信息"""
14
    if name in students:
15
        scores = students[name]
16
        average = calculate_average(scores)
17
        return f"{name} 的成绩：{scores}，平均分：{average:.2f}"
18
    else:
19
        return f"错误：找不到学生 {name}"
20

21
# 测试
22
print(get_student_info("张三"))
23
print(get_student_info("赵六"))

1
import requests
2

3
def get_weather(city):
4
    """获取天气信息（示例）"""
5
    try:
6
        # 使用免费的天气 API
7
        url = f"https://api.openweathermap.org/data/2.5/weather"
8
        params = {
9
            "q": city,
10
            "appid": "your-api-key",  # 需要替换为实际的 API Key
11
            "units": "metric",
12
            "lang": "zh_cn"
13
        }
14

15
        response = requests.get(url, params=params)
16
        response.raise_for_status()
17

18
        data = response.json()
19
        weather = data["weather"][0]["description"]
20
        temp = data["main"]["temp"]
21

22
        return f"{city} 的天气：{weather}，温度：{temp}°C"
23

24
    except requests.exceptions.RequestException as e:
25
        return f"获取天气失败：{e}"
26
    except KeyError:
27
        return "解析天气数据失败"
28

29
# 测试（需要有效的 API Key）
30
# print(get_weather("北京"))

1
import json
2

3
# 模拟 API 返回的数据
4
api_response = '''{
5
    "status": "success",
6
    "data": {
7
        "users": [
8
            {"id": 1, "name": "张三", "email": "zhangsan@example.com"},
9
            {"id": 2, "name": "李四", "email": "lisi@example.com"},
10
            {"id": 3, "name": "王五", "email": "wangwu@example.com"}
11
        ],
12
        "total": 3
13
    }
14
}'''
15

16
def parse_user_data(json_string):
17
    """解析用户数据"""
18
    try:
19
        data = json.loads(json_string)
20

21
        if data["status"] == "success":
22
            users = data["data"]["users"]
23
            print(f"共有 {data['data']['total']} 个用户：")
24

25
            for user in users:
26
                print(f"  - ID: {user['id']}, 姓名: {user['name']}, 邮箱: {user['email']}")
27
        else:
28
            print("API 返回失败")
29

30
    except json.JSONDecodeError:
31
        print("JSON 格式错误")
32
    except KeyError as e:
33
        print(f"数据格式错误：缺少字段 {e}")
34

35
# 测试
36
parse_user_data(api_response)

1
# 方法 1：使用 open() 和 read()
2
file = open("data.txt", "r", encoding="utf-8")
3
content = file.read()
4
print(content)
5
file.close()
6

7
# 方法 2：使用 with 语句（推荐）
8
# with 语句会自动关闭文件，即使发生异常
9
with open("data.txt", "r", encoding="utf-8") as file:
10
    content = file.read()
11
    print(content)
12

13
# 方法 3：逐行读取
14
with open("data.txt", "r", encoding="utf-8") as file:
15
    for line in file:
16
        print(line.strip())  # strip() 去除行尾的换行符

1
# 写入文本（覆盖模式）
2
with open("output.txt", "w", encoding="utf-8") as file:
3
    file.write("Hello, World!\n")
4
    file.write("你好，世界！")
5

6
# 追加内容
7
with open("output.txt", "a", encoding="utf-8") as file:
8
    file.write("\n这是追加的内容")
9

10
# 写入多行
11
lines = ["第一行", "第二行", "第三行"]
12
with open("output.txt", "w", encoding="utf-8") as file:
13
    file.writelines(line + "\n" for line in lines)

1
import json
2

3
# 写入 JSON 文件
4
data = {
5
    "name": "张三",
6
    "age": 25,
7
    "hobbies": ["读书", "游泳"]
8
}
9

10
with open("data.json", "w", encoding="utf-8") as file:
11
    json.dump(data, file, ensure_ascii=False, indent=2)
12

13
# 读取 JSON 文件
14
with open("data.json", "r", encoding="utf-8") as file:
15
    data = json.load(file)
16
    print(data)

1
import requests
2
import json
3

4
def fetch_and_save_data(url, filename):
5
    """获取数据并保存到文件"""
6
    try:
7
        # 发送请求
8
        response = requests.get(url)
9
        response.raise_for_status()
10

11
        # 保存到文件
12
        with open(filename, "w", encoding="utf-8") as file:
13
            json.dump(response.json(), file, ensure_ascii=False, indent=2)
14

15
        print(f"数据已保存到 {filename}")
16

17
    except requests.exceptions.RequestException as e:
18
        print(f"请求失败：{e}")
19
    except IOError as e:
20
        print(f"文件操作失败：{e}")
21

22
# 使用示例
23
# fetch_and_save_data("https://api.example.com/data", "response.json")

1
import os
2

3
if os.path.exists("data.txt"):
4
    with open("data.txt", "r") as file:
5
        content = file.read()
6
else:
7
    print("文件不存在")

1
# 传统方式
2
numbers = []
3
for i in range(10):
4
    numbers.append(i * 2)
5
print(numbers)  # [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
6

7
# 使用列表推导式
8
numbers = [i * 2 for i in range(10)]
9
print(numbers)  # [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

1
# 只保留偶数
2
numbers = [i for i in range(20) if i % 2 == 0]
3
print(numbers)  # [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
4

5
# 过滤列表中的字符串
6
items = ["apple", "banana", "cherry", "date", "elderberry"]
7
short_items = [item for item in items if len(item) < 6]
8
print(short_items)  # ['apple', 'date']

1
# 创建字典
2
numbers = [1, 2, 3, 4, 5]
3
squares = {num: num ** 2 for num in numbers}
4
print(squares)  # {1: 1, 2: 4, 3: 9, 4: 16, 5: 25}
5

6
# 转换字典大小写
7
original = {"name": "Alice", "age": 25, "city": "Beijing"}
8
upper_keys = {k.upper(): v for k, v in original.items()}
9
print(upper_keys)  # {'NAME': 'Alice', 'AGE': 25, 'CITY': 'Beijing'}

1
# 示例 1：处理 API 返回的数据
2
users = [
3
    {"name": "张三", "age": 25, "active": True},
4
    {"name": "李四", "age": 30, "active": False},
5
    {"name": "王五", "age": 28, "active": True},
6
    {"name": "赵六", "age": 22, "active": True}
7
]
8

9
# 获取所有活跃用户的名字
10
active_users = [user["name"] for user in users if user["active"]]
11
print(active_users)  # ['张三', '王五', '赵六']
12

13
# 获取所有用户的年龄
14
ages = [user["age"] for user in users]
15
print(ages)  # [25, 30, 28, 22]
16

17
# 计算平均年龄
18
average_age = sum(ages) / len(ages)
19
print(f"平均年龄：{average_age:.1f}")  # 平均年龄：26.2

1
# ❌ 不推荐：太复杂
2
result = [x * y for x in range(10) for y in range(10) if x * y > 50]
3

4
# ✅ 推荐：使用嵌套循环
5
result = []
6
for x in range(10):
7
    for y in range(10):
8
        if x * y > 50:
9
            result.append(x * y)

1
name = "张三"
2
age = 25
3

4
# 方法 1：使用 %（旧方法，不推荐）
5
message = "姓名：%s，年龄：%d" % (name, age)
6

7
# 方法 2：使用 format()
8
message = "姓名：{}，年龄：{}".format(name, age)
9

10
# 方法 3：使用 f-string（推荐，Python 3.6+）
11
message = f"姓名：{name}，年龄：{age}"
12

13
# f-string 支持表达式
14
message = f"明年年龄：{age + 1}"
15

16
# f-string 格式化数字
17
pi = 3.1415926
18
print(f"π ≈ {pi:.2f}")  # π ≈ 3.14
19
print(f"π ≈ {pi:.4f}")  # π ≈ 3.1416

1
# 交换两个变量的值
2
a, b = 10, 20
3
a, b = b, a  # 交换
4
print(a, b)  # 20 10
5

6
# 解包列表
7
numbers = [1, 2, 3]
8
x, y, z = numbers
9
print(x, y, z)  # 1 2 3
10

11
# 使用 * 解包剩余元素
12
numbers = [1, 2, 3, 4, 5]
13
first, *rest = numbers
14
print(first)  # 1
15
print(rest)   # [2, 3, 4, 5]
16

17
# 解包字典
18
user = {"name": "张三", "age": 25, "city": "北京"}
19
for key, value in user.items():
20
    print(f"{key}: {value}")

1
# 简单的计时装饰器
2
import time
3

4
def timer(func):
5
    def wrapper(*args, **kwargs):
6
        start = time.time()
7
        result = func(*args, **kwargs)
8
        end = time.time()
9
        print(f"{func.__name__} 执行时间：{end - start:.4f} 秒")
10
        return result
11
    return wrapper
12

13
# 使用装饰器
14
@timer
15
def slow_function():
16
    time.sleep(1)
17
    return "完成"
18

19
slow_function()  # 输出：slow_function 执行时间：1.000X 秒

1
# 传统方式：创建完整列表
2
def get_numbers传统(n):
3
    result = []
4
    for i in range(n):
5
        result.append(i ** 2)
6
    return result
7

8
# 使用生成器：按需生成
9
def get_numbers(n):
10
    for i in range(n):
11
        yield i ** 2
12

13
# 使用生成器
14
for num in get_numbers(10):
15
    print(num)
16

17
# 生成器表达式
18
squares = (i ** 2 for i in range(10))
19
print(list(squares))  # [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

1
# 普通函数
2
def add(x, y):
3
    return x + y
4

5
# Lambda 函数
6
add = lambda x, y: x + y
7
print(add(3, 5))  # 8
8

9
# 与 sorted() 结合使用
10
students = [
11
    {"name": "张三", "score": 85},
12
    {"name": "李四", "score": 92},
13
    {"name": "王五", "score": 78}
14
]
15

16
# 按分数排序
17
sorted_students = sorted(students, key=lambda x: x["score"], reverse=True)
18
print(sorted_students)

1
# 使用三引号
2
message = """
3
这是一个
4
多行字符串
5
示例
6
"""
7

8
# 使用括号
9
message = (
10
    "这是第一行\n"
11
    "这是第二行\n"
12
    "这是第三行"
13
)

1
fruits = ["苹果", "香蕉", "橙子"]
2

3
# 传统方式
4
for i in range(len(fruits)):
5
    print(f"{i}: {fruits[i]}")
6

7
# 使用 enumerate
8
for index, fruit in enumerate(fruits):
9
    print(f"{index}: {fruit}")
10

11
# 指定起始索引
12
for index, fruit in enumerate(fruits, start=1):
13
    print(f"{index}. {fruit}")

1
# Python 3.5+
2
dict1 = {"a": 1, "b": 2}
3
dict2 = {"c": 3, "d": 4}
4

5
# 方法 1：使用 update()
6
dict1.update(dict2)
7
print(dict1)
8

9
# 方法 2：使用 ** 解包
10
dict1 = {"a": 1, "b": 2}
11
dict2 = {"c": 3, "d": 4}
12
merged = {**dict1, **dict2}
13
print(merged)
14

15
# Python 3.9+
16
merged = dict1 | dict2
17
print(merged)

1
# 导入整个模块
2
import math
3
print(math.pi)  # 3.141592653589793
4
print(math.sqrt(16))  # 4.0
5

6
# 导入模块中的特定函数
7
from math import pi, sqrt
8
print(pi)
9
print(sqrt(16))
10

11
# 给模块起别名
12
import math as m
13
print(m.pi)
14

15
# 导入所有内容（不推荐）
16
from math import *

1
my_package/
2
    __init__.py
3
    module1.py
4
    module2.py

1
# datetime：日期时间处理
2
from datetime import datetime, timedelta
3

4
now = datetime.now()
5
print(now)  # 2024-01-11 10:30:00
6
print(now.strftime("%Y-%m-%d"))  # 2024-01-11
7

8
# random：随机数
9
import random
10
print(random.randint(1, 100))  # 1-100 之间的随机整数
11
print(random.choice(["苹果", "香蕉", "橙子"]))  # 随机选择
12

13
# os：操作系统相关
14
import os
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print(os.getcwd())  # 获取当前工作目录
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print(os.listdir())  # 列出当前目录的文件
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# pathlib：路径操作（推荐）
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from pathlib import Path
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path = Path("data.txt")
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print(path.exists())  # 检查文件是否存在
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print(path.name)  # 获取文件名