Case1-用list写shoppingcart

#define product list
product_list = [
    ('Python book',45),
    ('iphone',5800),
    ('iwatch', 1500),
    ("bike",850),
    ("luckiin coffee",25)
]
_shop =[]

#input customer salary
salary = input("Please input your Salary!》》》：")
if salary.isdigit():
    _salary = int(salary)

    while True:
        for index,item in enumerate(product_list):  # 输入正确数字salary，打印product list
            #print(product_list.index(item),item)
            print(index,item)
            print("\t")
        _choice = input("Please choice and Press 'q' to exit》》》:")

        if _choice.isdigit():
            _choice = int(_choice)

            if _choice <len(product_list ) and _choice>=0: #判读list范围
                p_item = product_list[_choice]
                if p_item[1]<=_salary: #钱够
                    _shop.append(p_item)  #添加记录到_shop 列表中
                    _salary -= p_item[1]  #扣钱
                    print("Add %s in shopping cart! Your current balance is \033[31;1m%s\033[0m" %(p_item, _salary))
                else:
                    print("Not Enough Money!!!")
            else:
                print("商品 %s 不存在！！" %(_choice))

        elif _choice == 'q':
            print("------shopping list---------")
            for p in _shop:
                print (_shop)
            print("Exit!")
            exit()
        else:
            print("Invalid number!")
            break  #注意break的位置

else:
    print("Invalid Salary!!!")
    salary = input("Please input your Salary!》》》：")



###目前还有一个问题就是错误按键就退出，没有给用户重新input的机会！