Python 脚本学习：15个由简入繁的实用示例
学习路径建议
- 初级阶段 (示例1-5): 掌握Python基础语法、流程控制、函数和数据结构
- 中级阶段 (示例6-10): 学习面向对象编程、异常处理、文件操作和API调用
- 高级阶段 (示例11-15): 掌握并发编程、装饰器、上下文管理器和综合项目开发
示例1: 基础Hello World和用户输入
# 最简单的Python程序 - 输出和输入处理
name = input("请输入你的名字: ")
print(f"你好, {name}! 欢迎学习Python!")
age = int(input("请输入你的年龄: "))
print(f"明年你将 {age + 1} 岁")
# 学习要点: 输入输出、字符串格式化、类型转换
示例2: 条件判断和循环
# 猜数字游戏 - 条件判断和循环
import random
number = random.randint(1, 100)
attempts = 0
max_attempts = 7
print("猜数字游戏! 我想了一个1到100之间的数字")
while attempts < max_attempts:
guess = int(input("你的猜测是: "))
attempts += 1
if guess < number:
print("太小了!")
elif guess > number:
print("太大了!")
else:
print(f"恭喜! 你在{attempts}次尝试中猜对了!")
break
else:
print(f"抱歉，你没有在{max_attempts}次尝试内猜对。数字是{number}")
# 学习要点: 条件语句、循环、随机数、break/else在循环中的应用
示例3: 文件操作
# 文件读写操作 - 日记程序
import datetime
def write_diary():
entry = input("请输入今天的日记: ")
today = datetime.datetime.now().strftime("%Y-%m-%d %H:%M")
with open("diary.txt", "a", encoding="utf-8") as file:
file.write(f"{today}\n{entry}\n\n")
print("日记已保存!")
def read_diary():
try:
with open("diary.txt", "r", encoding="utf-8") as file:
content = file.read()
print("\n=== 我的日记 ===")
print(content)
except FileNotFoundError:
print("还没有日记记录!")
# 主程序
while True:
print("\n1. 写日记")
print("2. 读日记")
print("3. 退出")
choice = input("请选择操作: ")
if choice == "1":
write_diary()
elif choice == "2":
read_diary()
elif choice == "3":
break
else:
print("无效选择!")
# 学习要点: 文件读写、异常处理、日期时间处理、菜单驱动程序
示例4: 函数和模块化编程
# 计算器程序 - 函数和模块化
def add(a, b):
return a + b
def subtract(a, b):
return a - b
def multiply(a, b):
return a * b
def divide(a, b):
if b == 0:
return "错误: 除数不能为零"
return a / b
def calculator():
print("简易计算器")
print("操作: +, -, *, /")
try:
num1 = float(input("输入第一个数字: "))
operator = input("输入操作符: ")
num2 = float(input("输入第二个数字: "))
if operator == "+":
result = add(num1, num2)
elif operator == "-":
result = subtract(num1, num2)
elif operator == "*":
result = multiply(num1, num2)
elif operator == "/":
result = divide(num1, num2)
else:
result = "无效操作符"
print(f"结果: {result}")
except ValueError:
print("错误: 请输入有效数字")
# 运行计算器
if __name__ == "__main__":
calculator()
# 学习要点: 函数定义、模块化设计、错误处理、if-elif-else结构
示例5: 列表和字典操作
# 学生成绩管理系统 - 列表和字典操作
students = []
def add_student():
name = input("输入学生姓名: ")
grades = []
while True:
grade = input("输入成绩(输入'done'结束): ")
if grade.lower() == 'done':
break
try:
grades.append(float(grade))
except ValueError:
print("请输入有效数字!")
student = {"name": name, "grades": grades, "average": sum(grades)/len(grades) if grades else 0}
students.append(student)
print(f"学生 {name} 已添加!")
def show_students():
if not students:
print("没有学生记录!")
return
print("\n=== 学生成绩表 ===")
for student in students:
print(f"{student['name']}: 成绩{student['grades']}, 平均分{student['average']:.2f}")
def find_top_student():
if not students:
print("没有学生记录!")
return
top_student = max(students, key=lambda x: x['average'])
print(f"最高分学生: {top_student['name']}, 平均分: {top_student['average']:.2f}")
# 主程序
while True:
print("\n1. 添加学生")
print("2. 显示所有学生")
print("3. 显示最高分学生")
print("4. 退出")
choice = input("请选择操作: ")
if choice == "1":
add_student()
elif choice == "2":
show_students()
elif choice == "3":
find_top_student()
elif choice == "4":
break
else:
print("无效选择!")
# 学习要点: 列表和字典操作、lambda函数、数据管理
示例6: 面向对象编程
# 银行账户系统 - 面向对象编程
class BankAccount:
def __init__(self, account_holder, initial_balance=0):
self.account_holder = account_holder
self.balance = initial_balance
self.transactions = []
def deposit(self, amount):
if amount > 0:
self.balance += amount
self.transactions.append(f"存款: +${amount}")
return True
return False
def withdraw(self, amount):
if 0 < amount <= self.balance:
self.balance -= amount
self.transactions.append(f"取款: -${amount}")
return True
return False
def get_balance(self):
return self.balance
def get_transaction_history(self):
return self.transactions
# 创建和使用账户
account = BankAccount("张三", 1000)
print(f"账户持有人: {account.account_holder}")
print(f"初始余额: ${account.get_balance()}")
account.deposit(500)
account.withdraw(200)
account.withdraw(1500) # 这个会失败，余额不足
print(f"当前余额: ${account.get_balance()}")
print("交易记录:")
for transaction in account.get_transaction_history():
print(transaction)
# 学习要点: 类定义、构造函数、方法、封装、对象使用
示例7: 异常处理和自定义异常
# 自定义异常和错误处理
class InsufficientFundsError(Exception):
"""自定义异常：余额不足"""
pass
class BankAccount:
def __init__(self, balance=0):
self.balance = balance
def withdraw(self, amount):
if amount > self.balance:
raise InsufficientFundsError(f"余额不足! 当前余额: ${self.balance}, 尝试取款: ${amount}")
self.balance -= amount
return amount
# 使用自定义异常
account = BankAccount(100)
print(f"初始余额: ${account.balance}")
try:
account.withdraw(50)
print(f"取款成功! 当前余额: ${account.balance}")
account.withdraw(100) # 这会引发异常
print(f"取款成功! 当前余额: ${account.balance}")
except InsufficientFundsError as e:
print(f"取款失败: {e}")
except Exception as e:
print(f"发生未知错误: {e}")
# 学习要点: 自定义异常、异常处理、raise语句
示例8: 文件处理和CSV操作
# CSV文件处理 - 员工管理系统
import csv
import os
def add_employee():
name = input("员工姓名: ")
position = input("职位: ")
salary = input("薪资: ")
with open('employees.csv', 'a', newline='', encoding='utf-8') as file:
writer = csv.writer(file)
writer.writerow([name, position, salary])
print("员工已添加!")
def list_employees():
if not os.path.exists('employees.csv'):
print("没有员工记录!")
return
with open('employees.csv', 'r', encoding='utf-8') as file:
reader = csv.reader(file)
print("\n=== 员工列表 ===")
for i, row in enumerate(reader, 1):
print(f"{i}. {row[0]} - {row[1]} - ${row[2]}")
def calculate_payroll():
if not os.path.exists('employees.csv'):
print("没有员工记录!")
return
total_payroll = 0
with open('employees.csv', 'r', encoding='utf-8') as file:
reader = csv.reader(file)
for row in reader:
try:
total_payroll += float(row[2])
except ValueError:
print(f"警告: 无效的薪资数据 '{row[2]}' 对于员工 {row[0]}")
print(f"总薪资支出: ${total_payroll:.2f}")
# 主程序
while True:
print("\n1. 添加员工")
print("2. 列出所有员工")
print("3. 计算总薪资")
print("4. 退出")
choice = input("请选择操作: ")
if choice == "1":
add_employee()
elif choice == "2":
list_employees()
elif choice == "3":
calculate_payroll()
elif choice == "4":
break
else:
print("无效选择!")
# 学习要点: CSV文件处理、文件存在性检查、枚举、错误处理
示例9: 正则表达式应用
# 正则表达式应用 - 数据验证和提取
import re
def validate_email(email):
pattern = r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$'
return re.match(pattern, email) is not None
def validate_phone(phone):
pattern = r'^(\+?\d{1,3}[-.\s]?)?\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$'
return re.match(pattern, phone) is not None
def extract_emails(text):
pattern = r'[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}'
return re.findall(pattern, text)
# 测试函数
test_emails = ["test@example.com", "invalid.email", "name@domain.co.uk"]
test_phones = ["123-456-7890", "(123) 456-7890", "1234567890", "invalid"]
test_text = "联系我们: support@example.com 或 sales@company.com"
print("邮箱验证:")
for email in test_emails:
print(f"{email}: {'有效' if validate_email(email) else '无效'}")
print("\n电话验证:")
for phone in test_phones:
print(f"{phone}: {'有效' if validate_phone(phone) else '无效'}")
print("\n提取邮箱:")
emails = extract_emails(test_text)
print(f"找到邮箱: {emails}")
# 学习要点: 正则表达式、模式匹配、数据验证、文本提取
示例10: 网络请求和API调用
# 天气查询程序 - 网络请求和API调用
import requests
import json
def get_weather(city):
api_key = "your_api_key" # 需要替换为实际的API密钥
base_url = "http://api.openweathermap.org/data/2.5/weather"
params = {
'q': city,
'appid': api_key,
'units': 'metric' # 使用摄氏度
}
try:
response = requests.get(base_url, params=params)
response.raise_for_status() # 如果请求失败，抛出异常
data = response.json()
if data['cod'] != 200:
return f"错误: {data['message']}"
weather = {
'city': data['name'],
'country': data['sys']['country'],
'temperature': data['main']['temp'],
'description': data['weather'][0]['description'],
'humidity': data['main']['humidity'],
'wind': data['wind']['speed']
}
return weather
except requests.exceptions.RequestException as e:
return f"网络请求错误: {e}"
except (KeyError, IndexError) as e:
return f"数据解析错误: {e}"
# 使用示例
city = input("请输入城市名称: ")
weather = get_weather(city)
if isinstance(weather, dict):
print(f"\n{weather['city']}, {weather['country']} 的天气:")
print(f"温度: {weather['temperature']}°C")
print(f"天气: {weather['description']}")
print(f"湿度: {weather['humidity']}%")
print(f"风速: {weather['wind']} m/s")
else:
print(weather)
# 学习要点: HTTP请求、API调用、JSON处理、异常处理
示例11: 多线程编程
# 多线程下载器 - 并发编程
import threading
import time
import random
def download_file(filename, size):
"""模拟文件下载"""
print(f"开始下载 {filename} (大小: {size}MB)")
for i in range(1, 11):
time.sleep(random.uniform(0.1, 0.5)) # 模拟下载时间
progress = i * 10
print(f"{filename}: {progress}% 完成")
print(f"{filename} 下载完成!")
# 创建多个下载任务
files = [
("document.pdf", 5),
("image.jpg", 3),
("video.mp4", 50),
("music.mp3", 8)
]
threads = []
# 创建并启动线程
for filename, size in files:
thread = threading.Thread(target=download_file, args=(filename, size))
threads.append(thread)
thread.start()
# 等待所有线程完成
for thread in threads:
thread.join()
print("所有文件下载完成!")
# 学习要点: 多线程编程、线程创建和管理、并发执行
示例12: 装饰器和函数高级特性
# 装饰器应用 - 函数计时和缓存
import time
import functools
def timer(func):
"""计算函数执行时间的装饰器"""
@functools.wraps(func)
def wrapper(*args, **kwargs):
start_time = time.time()
result = func(*args, **kwargs)
end_time = time.time()
print(f"{func.__name__} 执行时间: {end_time - start_time:.4f}秒")
return result
return wrapper
def cache(func):
"""函数结果缓存装饰器"""
cached_results = {}
@functools.wraps(func)
def wrapper(*args):
if args in cached_results:
print(f"使用缓存结果 for {args}")
return cached_results[args]
result = func(*args)
cached_results[args] = result
return result
return wrapper
@timer
@cache
def fibonacci(n):
"""计算斐波那契数列"""
if n < 2:
return n
return fibonacci(n-1) + fibonacci(n-2)
# 测试装饰器
print("计算斐波那契数列:")
for i in range(10):
result = fibonacci(i)
print(f"fib({i}) = {result}")
# 学习要点: 装饰器、函数包装、缓存、递归、函数计时
示例13: 上下文管理器
# 自定义上下文管理器 - 数据库连接模拟
class DatabaseConnection:
def __init__(self, db_name):
self.db_name = db_name
self.connected = False
def __enter__(self):
"""进入上下文时调用"""
print(f"连接到数据库 {self.db_name}...")
self.connected = True
# 这里模拟实际的数据库连接操作
return self
def execute_query(self, query):
"""执行查询"""
if not self.connected:
raise Exception("未连接到数据库")
print(f"执行查询: {query}")
# 这里模拟查询执行和返回结果
return f"查询 '{query}' 的结果"
def __exit__(self, exc_type, exc_val, exc_tb):
"""退出上下文时调用"""
print("关闭数据库连接...")
self.connected = False
# 如果发生异常，可以在这里处理
if exc_type:
print(f"发生异常: {exc_val}")
# 返回False会让异常继续传播，True会抑制异常
return False
# 使用上下文管理器
try:
with DatabaseConnection("my_database") as db:
result1 = db.execute_query("SELECT * FROM users")
print(result1)
result2 = db.execute_query("SELECT * FROM products")
print(result2)
# 这里故意引发一个异常
# raise Exception("测试异常")
except Exception as e:
print(f"捕获到异常: {e}")
# 学习要点: 上下文管理器、with语句、资源管理、异常处理
示例14: 数据可视化
# 数据可视化 - 使用matplotlib绘制图表
import matplotlib.pyplot as plt
import numpy as np
# 创建示例数据
x = np.linspace(0, 10, 100)
y1 = np.sin(x)
y2 = np.cos(x)
y3 = np.sin(x) * np.cos(x)
# 创建图表和子图
fig, (ax1, ax2, ax3) = plt.subplots(3, 1, figsize=(10, 8))
fig.suptitle('三角函数可视化', fontsize=16)
# 绘制正弦函数
ax1.plot(x, y1, 'r-', label='sin(x)')
ax1.set_title('正弦函数')
ax1.set_xlabel('x')
ax1.set_ylabel('sin(x)')
ax1.legend()
ax1.grid(True)
# 绘制余弦函数
ax2.plot(x, y2, 'b--', label='cos(x)')
ax2.set_title('余弦函数')
ax2.set_xlabel('x')
ax2.set_ylabel('cos(x)')
ax2.legend()
ax2.grid(True)
# 绘制正弦余弦乘积
ax3.plot(x, y3, 'g-.', label='sin(x)*cos(x)')
ax3.set_title('正弦余弦乘积')
ax3.set_xlabel('x')
ax3.set_ylabel('sin(x)*cos(x)')
ax3.legend()
ax3.grid(True)
# 调整布局并显示图表
plt.tight_layout()
plt.savefig('trig_functions.png') # 保存图表
plt.show()
# 学习要点: 数据可视化、matplotlib使用、子图创建、图表定制
示例15: 综合项目 - 简易博客系统
# 简易博客系统 - 综合应用
import json
import os
from datetime import datetime
class Blog:
def __init__(self, data_file="blog_data.json"):
self.data_file = data_file
self.posts = self.load_posts()
def load_posts(self):
"""从文件加载博客文章"""
if os.path.exists(self.data_file):
try:
with open(self.data_file, 'r', encoding='utf-8') as file:
return json.load(file)
except (json.JSONDecodeError, IOError):
return []
return []
def save_posts(self):
"""保存博客文章到文件"""
try:
with open(self.data_file, 'w', encoding='utf-8') as file:
json.dump(self.posts, file, ensure_ascii=False, indent=2)
return True
except IOError:
return False
def add_post(self, title, content, author):
"""添加新文章"""
post = {
'id': len(self.posts) + 1,
'title': title,
'content': content,
'author': author,
'date': datetime.now().strftime("%Y-%m-%d %H:%M"),
'comments': []
}
self.posts.append(post)
return self.save_posts()
def get_posts(self):
"""获取所有文章"""
return self.posts
def get_post(self, post_id):
"""根据ID获取文章"""
for post in self.posts:
if post['id'] == post_id:
return post
return None
def add_comment(self, post_id, comment, author):
"""添加评论"""
post = self.get_post(post_id)
if post:
post['comments'].append({
'author': author,
'comment': comment,
'date': datetime.now().strftime("%Y-%m-%d %H:%M")
})
return self.save_posts()
return False
def display_posts(posts):
"""显示文章列表"""
if not posts:
print("暂无文章!")
return
for post in posts:
print(f"\n[{post['id']}] {post['title']}")
print(f"作者: {post['author']} | 日期: {post['date']}")
print(f"内容: {post['content'][:50]}...")
print(f"评论数: {len(post['comments'])}")
def display_post(post):
"""显示单篇文章详情"""
if not post:
print("文章不存在!")
return
print(f"\n标题: {post['title']}")
print(f"作者: {post['author']} | 日期: {post['date']}")
print(f"内容: {post['content']}")
print("\n评论:")
if post['comments']:
for comment in post['comments']:
print(f" - {comment['author']} ({comment['date']}): {comment['comment']}")
else:
print(" 暂无评论")
# 主程序
def main():
blog = Blog()
while True:
print("\n=== 简易博客系统 ===")
print("1. 查看所有文章")
print("2. 查看文章详情")
print("3. 发布新文章")
print("4. 添加评论")
print("5. 退出")
choice = input("请选择操作: ")
if choice == "1":
posts = blog.get_posts()
display_posts(posts)
elif choice == "2":
try:
post_id = int(input("输入文章ID: "))
post = blog.get_post(post_id)
display_post(post)
except ValueError:
print("请输入有效的文章ID!")
elif choice == "3":
title = input("文章标题: ")
content = input("文章内容: ")
author = input("作者姓名: ")
if blog.add_post(title, content, author):
print("文章发布成功!")
else:
print("文章发布失败!")
elif choice == "4":
try:
post_id = int(input("输入文章ID: "))
comment = input("评论内容: ")
author = input("你的姓名: ")
if blog.add_comment(post_id, comment, author):
print("评论添加成功!")
else:
print("评论添加失败!")
except ValueError:
print("请输入有效的文章ID!")
elif choice == "5":
print("感谢使用博客系统!")
break
else:
print("无效选择!")
if __name__ == "__main__":
main()
# 学习要点: 类设计、JSON数据持久化、菜单系统、数据管理、模块化编程
每个示例都展示了Python编程的不同方面，建议你逐个尝试并理解其中的概念。通过修改和扩展这些示例，你可以更深入地掌握Python编程技巧。
