python中對列表和循環使用的小練習

#author devilf

product_list = [
    ('iphone',5800),
    ('Mac Pro',9800),
    ('Bike',800),
    ('Watch',10000),
    ('Coffee',123)
]
shop_list = []
salary = input('pls enter your salary: ')

if salary.isdigit():                    #判斷是否爲整形，不然會退出
    salary = int(salary)
    while True:
        for index,info in enumerate(product_list):                  #打印列表
#            print(product_list.index(info),info)
            print(index,info)
        user_choice = input('pls enter what you buy\n>>>: ')        #輸入要購買的商品 編號
        if user_choice.isdigit():                   #再判斷下輸入的是不是數字，不然退出
            user_choice = int(user_choice)
            if user_choice <= len(product_list) and user_choice >= 0:       #判斷輸入的編號是否在商品列表的編號範圍內
                p_item = product_list[user_choice]              #取出編號對應的商品名稱
                if p_item[1] <= salary:             #判斷改商品的價格是否在工資範圍內
                    shop_list.append(p_item)        #若是在工資範圍內，購買！
                    salary -= p_item[1]             #總工資便會減小對應的錢
                    print('Added %s into shopping cart,your current balance is %s' %(p_item,salary))
                else:
                    print('your current balance is %s ,now is not enough' % (salary))
            else:
                print('product %s is not exist!' % user_choice )
        elif user_choice == 'q':                    #若是輸入的是 'q'，便會退出
            print('-------------shopping list------------')
            for p in shop_list:
                print(p)
            print('quit.....,your current money: ',salary)
            exit()
        else:
            print('Invalid option')