Python新手求助：如何高效实现商店订单自动计算总价（支持多商品）

问题描述 #

刚学习Python两天，编写了一个简易的商店程序，用户下单后程序会告知总价。目前通过if语句实现了单商品及特定组合的总价展示，但该方法效率低下，且无法自动计算任意多种商品组合的总价，附上原始代码：

print("Welcome to the Apple Store!")

name = input("What is your name?\n")

print("Hello " + name + ", welcome to the Apple store!\n\n")

products = "iPhone 14 $10,000, Macbook Air $14,000, iPhone 13 $8,000\n"

value = input

iPhone_14 = 10000
Macbook_Air = 14000
iPhone_13 = 8000

a = iPhone_14 + Macbook_Air


order = input("Here is our list of products, what would you want?\n" + products)

if order == "iPhone 14":
    print("Alright " + name + ", your " + order + " will be prepared.\n\n" + "The total amount will be " + str(iPhone_14))

if order == "Macbook Air":
    print("Alright " + name + ", your " + order + " will be prepared.\n\n" + "The total amount will be " + str(Macbook_Air))

if order == "iPhone 13":
    print("Alright " + name + ", your " + order + " will be prepared.\n\n" + "The total amount will be " + str(iPhone_13))

if order == "iPhone 14, Macbook Air":
    print("Alright " + name + ", your " + order + " will be prepared.\n\n" + "The total amount will be " + str(a))

优化思路与解决方案 #

• 用字典存储商品信息：将商品名称和对应价格存入字典，实现快速查找，后续新增商品只需修改字典，无需添加大量判断语句。
• 标准化输入处理：将用户输入的订单按逗号拆分，去除每个商品名称前后的空格，确保能匹配字典中的键。
• 自动计算总价：遍历拆分后的商品列表，累加对应价格，同时区分有效和无效商品，提升程序健壮性。

优化后的完整代码 #

print("Welcome to the Apple Store!")

name = input("What is your name?\n")
print(f"Hello {name}, welcome to the Apple store!\n\n")

# 字典存储商品与价格，便于扩展和查询
product_prices = {
    "iPhone 14": 10000,
    "Macbook Air": 14000,
    "iPhone 13": 8000
}

# 自动生成商品列表字符串，避免手动拼接
products = ", ".join([f"{item} ${price:,}" for item, price in product_prices.items()]) + "\n"

order_input = input(f"Here is our list of products, what would you want?\n{products}")

# 拆分输入并清理空格，得到商品列表
ordered_items = [item.strip() for item in order_input.split(",")]

total = 0
valid_items = []
invalid_items = []

# 遍历订单计算总价，区分有效/无效商品
for item in ordered_items:
    if item in product_prices:
        total += product_prices[item]
        valid_items.append(item)
    else:
        invalid_items.append(item)

# 输出结果
if valid_items:
    items_str = ", ".join(valid_items)
    print(f"Alright {name}, your {items_str} will be prepared.\n\nThe total amount will be ${total:,}")

if invalid_items:
    invalid_str = ", ".join(invalid_items)
    print(f"Note: {invalid_str} are not available in our store.")

优化点说明 #

• 扩展性强：新增商品只需在product_prices字典中添加键值对，无需修改核心逻辑。
• 支持任意组合：无论用户输入多少种商品组合，都能自动计算总价。
• 错误提示：识别无效商品并告知用户，提升用户体验。
• 格式优化：用f-string简化字符串拼接，价格带千位分隔符更直观。

内容的提问来源于stack exchange，提问作者eden