编辑代码

class StainlessSteelInventory:
    def __init__(self):
        self.inventory = {}

    def add_item(self, item_name, quantity):
        if item_name in self.inventory:
            self.inventory[item_name] += quantity
        else:
            self.inventory[item_name] = quantity

    def remove_item(self, item_name, quantity):
        if item_name in self.inventory:
            if self.inventory[item_name] >= quantity:
                self.inventory[item_name] -= quantity
                if self.inventory[item_name] == 0:
                    del self.inventory[item_name]
            else:
                print("库存不足，无法删除指定数量的物品。")
        else:
            print("库存中不存在该物品。")

    def query_item(self, item_name):
        if item_name in self.inventory:
            print(f"{item_name} 的库存数量为: {self.inventory[item_name]}")
        else:
            print("库存中不存在该物品。")

    def show_inventory(self):
        for item, quantity in self.inventory.items():
            print(f"{item}: {quantity}")

# 测试代码
inventory_system = StainlessSteelInventory()

# 添加物品
inventory_system.add_item("不锈钢板", 50)
inventory_system.add_item("不锈钢管", 30)

# 查询物品
inventory_system.query_item("不锈钢板")

# 显示库存
inventory_system.show_inventory()

# 删除物品
inventory_system.remove_item("不锈钢板", 20)

# 再次显示库存
inventory_system.show_inventory()