Python初探-购物车程序

print("------------******-----------")
menu = [["macbook",9000],["iphone",4500],["bick",800],["pythonbook",80],["cup",50]]
shopping_car = []
a = True
while a == True:
    balance = input("请输入您拥有的金额[q退出]:")
    if balance.isdigit():
        balance = int(balance)
        while True:
            for i in range(0,len(menu)):
                print(str(i + 1) + "、" + menu[i][0],menu[i][1])
            choice = (input("请您输入需要的商品序号[q退出]"))
            if choice.isdigit():
                choice = int(choice)
                if 0 < choice <= len(menu):

                    price = int(menu[choice - 1][1])
                    if price <= balance:
                        balance -= price
                        shopping_car.append(menu[choice - 1])
                        print("已添加" + str(menu[choice - 1][0]) + "到您的购物车,余额" + str(balance) +"。请继续购物。")
                    else:
                        print("余额不足" + str(balance - price) + "请重新选择。")
            elif choice == "q":
                print("您购买了以下商品")
                for i in range(0, len(shopping_car)):
                    print(str(i + 1) + "、" + shopping_car[i][0], shopping_car[i][1])
                print("当前余额为:" + str(balance))
                a = False
                break
            else:
                print("请输入正确的编号")
    elif balance == "q":
        print("您未购买商品。")
        break
    else:
        print("请输入正确的金额")