#此次购物车优化，主要使用了文件操作的相关方法。

#有买家入口，和商家入口

#买家入口

#买家第一次启动程序输入金额，金额会记录到文件里，再登录就读取文件里保存的金额，买家可以购买商品，按 ‘q’ 退出后显示购买的商品和余额，并保存购买过的商品和余额。

global data
global userinformation
money=‘‘
data=‘data.txt‘
userinformation=‘userinformation.txt‘
mgoods=[]
exit_flag = False
def shuoppxit(money):
    if money.isdigit():
        while not exit_flag:
            for index, item in enumerate(goods):
                print(index, item)
            numbres = input("输入购买商品的序号：")
            if numbres.isdigit():
                numbres = int(numbres)
                if numbres< len(goods) and numbres >=0:
                    money = int(money)
                    numbres_goods=goods[numbres][1]
                    if money >= numbres_goods:
                        money=money-numbres_goods
                        goods[numbres].append(‘余额‘)
                        goods[numbres].append(money)
                        print(goods[numbres])
                        mgoods.append(goods[numbres])
                        f = open(userinformation, ‘w+‘, encoding=‘utf-8‘)
                        f.write(str(mgoods))
                        f.close()
                        print(‘购买商品成功:‘+goods[numbres][0])
                        print(‘剩余金钱：\033[31;1m %s \33[0m‘ % money )
                    else:
                        print(‘余额不足！‘)
            elif numbres==‘q‘ or numbres==‘Q‘:
                print(‘你购买的商品如下：‘)
                f = open(userinformation, ‘r‘, encoding=‘utf-8‘)
                data2 = f.read()
                goods2 = eval(data2)
                for i in goods2:
                    print(i)
                break
            else:
                print(‘输入错误！！‘)
    else:
        print(‘输入错误！！,重新输入‘)
        
f = open(data,‘r‘,encoding=‘utf-8‘)
data2 = f.read()
goods = eval(data2)

f = open(userinformation,‘r‘,encoding=‘utf-8‘)
data2 = f.read()
if data2 !=‘‘:
    usernames = eval(data2)
    money= usernames[0][3]
    money=str(money)
    shuoppxit(money)
else:
    money = input("输入你的钱：")
    shuoppxit(money)

#商家入口
#商家可以添加产品，和修改价格

global data
money=‘‘
data=‘data.txt‘
mgoods=[]
exit_flag = False

f = open(data,‘r‘,encoding=‘utf-8‘)
data2 = f.read()
goods = eval(data2)
print(goods)
while not exit_flag:
    choice=input(‘1、添加商品 2、修改价格：‘)
    if choice.isdigit():
        if choice==‘1‘:
            name=input(‘输入商品名：‘)
            price=input(‘输入价格：‘)
            mgoods.append(name)
            mgoods.append(price)
            goods.append(mgoods)
            f = open(data, ‘w‘, encoding=‘utf-8‘)
            f.write(str(goods))
            f.close()
            print(goods)
        else:
            for index, item in enumerate(goods):
                print(index, item)
                numbres = input("输入修改商品的序号：")
                if numbres.isdigit():
                    numbres = int(numbres)
                    if numbres < len(goods) and numbres >= 0:
                        jiage = input("输入修改商品价格：")
                        if jiage.isdigit():
                            jiage = int(jiage)
                            goods[numbres][1]= jiage
                            f = open(data, ‘w‘, encoding=‘utf-8‘)
                            f.write(str(goods))
                            f.close()
                            print(goods)
                            exit_flag=True

学习无止境，加油

python-文件操作-之优化购物车

原文：https://www.cnblogs.com/km-thonder/p/12389806.html