面向对象编程（OOP）是一种编程范式，它将数据及其操作封装在一起形成对象。OOP在处理复杂问题时尤其有用，因为它使得代码更加模块化、可重用和易于维护。以下是一些日常小问题的面向对象编程解决方案，通过10个实用例题，帮助你入门面向对象编程。
例题1：停车场管理系统
问题描述： 设计一个停车场管理系统，能够记录车辆进入和离开的时间，并计算停车费用。
解决方案：
class Car:
def __init__(self, license_plate, entry_time):
self.license_plate = license_plate
self.entry_time = entry_time
class ParkingLot:
def __init__(self, capacity):
self.capacity = capacity
self.cars = []
def enter(self, car):
if len(self.cars) < self.capacity:
self.cars.append(car)
print(f"Car {car.license_plate} entered at {car.entry_time}.")
else:
print("Parking lot is full.")
def leave(self, license_plate):
for car in self.cars:
if car.license_plate == license_plate:
print(f"Car {license_plate} left at {car.entry_time}.")
self.cars.remove(car)
return
print("Car not found in parking lot.")
# 使用示例
parking_lot = ParkingLot(5)
parking_lot.enter(Car("ABC123", "09:00"))
parking_lot.leave("ABC123")
例题2：图书管理系统
问题描述： 设计一个简单的图书管理系统，可以添加图书、删除图书和查找图书。
解决方案：
class Book:
def __init__(self, title, author):
self.title = title
self.author = author
class Library:
def __init__(self):
self.books = []
def add_book(self, book):
self.books.append(book)
print(f"Book '{book.title}' by {book.author} added to the library.")
def remove_book(self, title):
for book in self.books:
if book.title == title:
self.books.remove(book)
print(f"Book '{title}' removed from the library.")
return
print(f"Book '{title}' not found in the library.")
def find_book(self, title):
for book in self.books:
if book.title == title:
return book
return None
# 使用示例
library = Library()
library.add_book(Book("The Great Gatsby", "F. Scott Fitzgerald"))
book = library.find_book("The Great Gatsby")
if book:
print(f"Found book: {book.title} by {book.author}")
例题3：待办事项列表
问题描述： 创建一个待办事项列表，用户可以添加任务、标记任务为完成，并删除任务。
解决方案：
class Task:
def __init__(self, description):
self.description = description
self.completed = False
def mark_as_completed(self):
self.completed = True
print(f"Task '{self.description}' marked as completed.")
class TodoList:
def __init__(self):
self.tasks = []
def add_task(self, task):
self.tasks.append(task)
print(f"Task '{task.description}' added to the todo list.")
def remove_task(self, description):
for task in self.tasks:
if task.description == description:
self.tasks.remove(task)
print(f"Task '{description}' removed from the todo list.")
return
print(f"Task '{description}' not found in the todo list.")
def get_tasks(self):
return [task for task in self.tasks if not task.completed]
# 使用示例
todo_list = TodoList()
todo_list.add_task(Task("Buy groceries"))
todo_list.add_task(Task("Read a book"))
todo_list.get_tasks() # ['Buy groceries', 'Read a book']
例题4：用户账户管理系统
问题描述： 设计一个用户账户管理系统，能够创建用户、更改密码和注销账户。
解决方案：
class User:
def __init__(self, username, password):
self.username = username
self.password = password
class AccountManager:
def __init__(self):
self.users = {}
def create_user(self, username, password):
if username in self.users:
print("Username already exists.")
return
self.users[username] = User(username, password)
print(f"User '{username}' created.")
def change_password(self, username, new_password):
if username in self.users:
self.users[username].password = new_password
print(f"Password for user '{username}' changed.")
else:
print(f"User '{username}' not found.")
def logout(self, username):
if username in self.users:
del self.users[username]
print(f"User '{username}' logged out.")
else:
print(f"User '{username}' not found.")
# 使用示例
account_manager = AccountManager()
account_manager.create_user("john_doe", "secure_password")
account_manager.change_password("john_doe", "new_secure_password")
account_manager.logout("john_doe")
例题5：订单管理系统
问题描述： 创建一个订单管理系统，允许用户添加商品到订单、更新订单和删除订单。
解决方案：
class Product:
def __init__(self, name, price):
self.name = name
self.price = price
class Order:
def __init__(self):
self.products = []
def add_product(self, product):
self.products.append(product)
print(f"Product '{product.name}' added to the order.")
def update_product_price(self, product_name, new_price):
for product in self.products:
if product.name == product_name:
product.price = new_price
print(f"Price of product '{product_name}' updated to {new_price}.")
return
print(f"Product '{product_name}' not found in the order.")
def remove_product(self, product_name):
for product in self.products:
if product.name == product_name:
self.products.remove(product)
print(f"Product '{product_name}' removed from the order.")
return
print(f"Product '{product_name}' not found in the order.")
# 使用示例
order = Order()
order.add_product(Product("Laptop", 1000))
order.update_product_price("Laptop", 1100)
order.remove_product("Laptop")
例题6：日历管理系统
问题描述： 实现一个简单的日历管理系统，允许用户添加事件、查看当天事件和删除事件。
解决方案：
from datetime import datetime
class Event:
def __init__(self, title, start_time, end_time):
self.title = title
self.start_time = start_time
self.end_time = end_time
class Calendar:
def __init__(self):
self.events = {}
def add_event(self, event):
self.events[event.start_time] = event
print(f"Event '{event.title}' added to the calendar.")
def get_events_for_day(self, day):
return [event for event in self.events.values() if event.start_time.date() == day]
def remove_event(self, event_title):
for event in self.events.values():
if event.title == event_title:
del self.events[event.start_time]
print(f"Event '{event_title}' removed from the calendar.")
return
print(f"Event '{event_title}' not found in the calendar.")
# 使用示例
calendar = Calendar()
today = datetime.now().date()
calendar.add_event(Event("Meeting", datetime.combine(today, datetime.min.time()), datetime.combine(today, datetime.max.time())))
events_today = calendar.get_events_for_day(today)
if events_today:
print("Today's events:")
for event in events_today:
print(f"- {event.title}")
例题7：银行账户管理系统
问题描述： 设计一个银行账户管理系统，支持创建账户、存款、取款和查看余额。
解决方案：
class Account:
def __init__(self, account_number, balance=0):
self.account_number = account_number
self.balance = balance
def deposit(self, amount):
self.balance += amount
print(f"Deposited {amount}. New balance: {self.balance}.")
def withdraw(self, amount):
if amount <= self.balance:
self.balance -= amount
print(f"Withdrew {amount}. New balance: {self.balance}.")
else:
print("Insufficient funds.")
def get_balance(self):
return self.balance
# 使用示例
account = Account("123456789")
account.deposit(1000)
account.withdraw(500)
print(f"Account balance: {account.get_balance()}")
例题8：在线商店购物车
问题描述： 创建一个在线商店购物车系统，允许用户添加商品到购物车、更新商品数量和删除商品。
解决方案：
class Product:
def __init__(self, name, price):
self.name = name
self.price = price
class ShoppingCart:
def __init__(self):
self.items = {}
def add_product(self, product, quantity):
if product.name in self.items:
self.items[product.name]['quantity'] += quantity
else:
self.items[product.name] = {'product': product, 'quantity': quantity}
print(f"Added {quantity} of '{product.name}' to the cart.")
def update_quantity(self, product_name, quantity):
if product_name in self.items:
self.items[product_name]['quantity'] = quantity
print(f"Updated quantity of '{product_name}' to {quantity}.")
else:
print(f"Product '{product_name}' not found in the cart.")
def remove_product(self, product_name):
if product_name in self.items:
del self.items[product_name]
print(f"Removed '{product_name}' from the cart.")
else:
print(f"Product '{product_name}' not found in the cart.")
# 使用示例
cart = ShoppingCart()
cart.add_product(Product("T-shirt", 20), 2)
cart.update_quantity("T-shirt", 3)
cart.remove_product("T-shirt")
例题9：会议预约系统
问题描述： 设计一个会议预约系统，用户可以预约会议、查看已预约的会议和取消预约。
解决方案：
from datetime import datetime
class Meeting:
def __init__(self, title, start_time, end_time):
self.title = title
self.start_time = start_time
self.end_time = end_time
class MeetingRoom:
def __init__(self):
self.bookings = {}
def book_meeting(self, meeting):
self.bookings[meeting.start_time] = meeting
print(f"Meeting '{meeting.title}' booked from {meeting.start_time} to {meeting.end_time}.")
def get_booked_meetings(self, day):
return [meeting for meeting in self.bookings.values() if meeting.start_time.date() == day]
def cancel_meeting(self, meeting_title):
for meeting in self.bookings.values():
if meeting.title == meeting_title:
del self.bookings[meeting.start_time]
print(f"Meeting '{meeting_title}' cancelled.")
return
print(f"Meeting '{meeting_title}' not found.")
# 使用示例
meeting_room = MeetingRoom()
meeting_room.book_meeting(Meeting("Project Review", datetime.now(), datetime.now() + timedelta(hours=2)))
booked_meetings_today = meeting_room.get_booked_meetings(datetime.now().date())
if booked_meetings_today:
print("Booked meetings today:")
for meeting in booked_meetings_today:
print(f"- {meeting.title}")
例题10：天气预报系统
问题描述： 创建一个简单的天气预报系统，能够查询特定日期的天气预报。
解决方案：
class WeatherForecast:
def __init__(self, day, temperature, description):
self.day = day
self.temperature = temperature
self.description = description
class WeatherService:
def __init__(self):
self.forecasts = {}
def get_forecast(self, day):
return self.forecasts.get(day, None)
def add_forecast(self, day, forecast):
self.forecasts[day] = forecast
print(f"Forecast for {day}: {forecast.description}, Temperature: {forecast.temperature}°C.")
# 使用示例
weather_service = WeatherService()
weather_service.add_forecast("Monday", WeatherForecast("Monday", 20, "Sunny"))
forecast = weather_service.get_forecast("Monday")
if forecast:
print(f"Weather forecast for Monday: {forecast.description}, Temperature: {forecast.temperature}°C.")
通过以上10个例题，你可以看到面向对象编程如何帮助我们解决日常生活中的小问题。面向对象编程的核心思想是将问题分解成更小的、更易于管理的部分，这些部分可以独立工作，同时保持整体的协调。通过这种方式，我们可以创建更加清晰、可维护和可扩展的代码。