要求：

用戶入口

1、商品信息存在文件里
2、已購商品，余額記錄。

商家入口

可以添加商品，修改商品價格

Code：

商家入口：

# Author:P J Jimport osps = '''1 >>>>>> 修改商品2 >>>>>> 添加商品按q為退出程序'''# 打開兩個文件，f文件為原來存取商品文件,f_new文件為修改后的商品文件f = open('commodit', 'r', encoding='utf-8')f_new = open('commodit_update', 'w+', encoding='utf-8')file_list = f.readlines()# 打印商品信息while True: productslist = [] # 從商品文件中讀取出來的數據存放到productslist列表里 for line in file_list:  productname = line.strip().split()  productname, oldprice = line.strip("/n").split()  productslist.append([productname, int(oldprice)]) choose = input("%s請選擇：" %ps) if choose =='1':  for index, item in enumerate(productslist):   print(index, item)  productindex = input("請輸入要修改價格的商品序號:")  if productindex.isdigit():   productindex = int(productindex)  while True:   print('要修改商品信息:', productslist[productindex])   price = input("請輸入要修改的價格:")   if price.isdigit():    price = int(price)    productslist[productindex][1]=price    break   else:    print("請正確的輸入價格！")    continue  #已經修改好的商品列表循環寫入f_new文件夾  for products in productslist:   insert_data = "%s %s" %(products[0],products[1])   f_new.write(insert_data+'/n')  print("商品價格已經修改！")  # 替換原來的文件  f_new = open('commodit_update', 'r', encoding='utf-8')  data = f_new.readlines()  f = open('commodit', 'w+', encoding='utf-8')  for line in data:   f.write(line)  f.close()  f_new.close()  #刪除替換文件  os.remove('commodit_update') elif choose =='2':  # 添加商品  f = open('commodit', 'a+', encoding='utf-8')  pricename = input("請輸入商品名:")  while True:   price = input("請輸入商品價格:")   if price.isdigit():    f.writelines('%s %s/n' % (pricename, price))    break   else:    print('輸入錯誤請重新輸入!')    continue  f.close()  continue elif choose =='q':  break else:  print("輸入錯誤請重新輸入")  continue

買家入口：

# Author:P J Jproductslist = []f = open('commodit','r',encoding='utf-8')for line in f: productname,price = line.strip('/n').split() productslist.append((productname,int(price)))print(productslist)shopping_list = []salary = input("請輸入你的現金:")if salary.isdigit(): salary = int(salary) while True:  # for item in productslist:  #  print(productslist.index(item),item)  for index,item in enumerate(productslist):   print(index,item)  #判斷用戶要輸入  user_choice = input("請選擇要買什啥>>>:")  if user_choice.isdigit():   user_choice = int(user_choice)   if user_choice < len(productslist) and user_choice >= 0:    p_item = productslist[user_choice]    if p_item[1] <= salary: #買得起     shopping_list.append(p_item)     salary -=p_item[1]     print("加入 %s 購物車你的余額是/033[31;1m%s/033[0mRMB" %(p_item,salary))    else:     print("/033[32;1m 你的余額只剩[%s]RMB啦，還買個毛線/033[0m " %salary)   else:    print("/033[41;1m您輸入的商品不存在，請重新輸入!/033[0m")  elif user_choice == 'q':   print("----shopping_list----")   for p in shopping_list:    print(p)   print("你的余額:/033[31;1m%s/033[0mRMB" %salary)   #簡單的余額記錄   f = open('salary','w+',encoding='utf-8')   f.writelines(str(salary))   f.close   exit()  else:   print("錯誤選項")