习题-购物车优化

 

lock_file = open('C:\\aaaaaaaaaaaaa\\custom.txt','r+')

lock = lock_file.read().split("\n")

print(lock)

 

usrname = input("请输入您的名字：")

not_new_custom = list(filter(lambda x: usrname in x, lock))

#print(not_new_custom)

if  not not_new_custom:

    salary = int(input("您是第一次访问，请输入你的salary:"))

    print("您现在的余额是：",salary)

else:

    print(usrname,",您好，欢迎回来")

    salary = not_new_custom[0]

    salary = salary.split(":")

    salary = int(salary[1])

    print("您现在的余额是：", salary)

 

lock_file_Commodity_shelves = open('C:\\aaaaaaaaaaaaa\\Commodity_shelves .txt','r+')

Commodity_shelves = lock_file_Commodity_shelves.read().split("\n")

print(Commodity_shelves)

shopping_car = []

buy_flag = 1

j = 0

while buy_flag:

    for i in Commodity_shelves:

        print(j,i)

        j +=1

    buy = input("请输入你要购买的商品编号,按q退出购物：")

    if buy == 'q':

        buy_flag = 0

        #break

    else:

        buy = int(buy)

        price = Commodity_shelves[buy]

        price = price.split(",")

        price = int(price[1])

        if salary > price:

 

            shopping_car.append(Commodity_shelves[buy])

            salary -= price

            print("你现在的余额是：",salary)

            print("你现在已经购买的东西有：",shopping_car)

        else:

            print("余额不足,现在的余额为：",salary,"按q退出购物")

    j = 0

if  not not_new_custom:

    lock_file.write(usrname + ":" + str(salary) + "\n")

    lock_file.close()

 

先把文件读出来，存在列表里，然后在每一个元素去判断是否包含指定的字符串，如果包含则不覆盖写入，跳过，不包含则覆盖写入文件

else:

    lock_file.close()

    with open("C:\\aaaaaaaaaaaaa\\custom.txt", "r", encoding="utf-8") as f:

 

        lines = f.readlines()

 

        # print(lines)

 

    with open("C:\\aaaaaaaaaaaaa\\custom.txt", "w", encoding="utf-8") as f_w:

 

        for line in lines:

 

            if usrname in line:

                continue

 

            f_w.write(line)

 

        f_w.write(usrname + ":" + str(salary) + "\n")