Python实现购物系统(示例讲解)

# Author:P J Jimport osps = '''1 >>>>>> 修改商品2 >>>>>> 添加商品按q为退出程序'''# 打开两个文件，f文件为原来存取商品文件,f_new文件为修改后的商品文件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 = [] # 从商品文件中读取出来的数据存放到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请选择：" %ps) if choose =='1':  for index, item in enumerate(productslist):   print(index, item)  productindex = input("请输入要修改价格的商品序号:")  if productindex.isdigit():   productindex = int(productindex)  while True:   print('要修改商品信息:', productslist[productindex])   price = input("请输入要修改的价格:")   if price.isdigit():    price = int(price)    productslist[productindex][1]=price    break   else:    print("请正确的输入价格！")    continue  #已经修改好的商品列表循环写入f_new文件夹  for products in productslist:   insert_data = "%s %s" %(products[0],products[1])   f_new.write(insert_data+'/n')  print("商品价格已经修改！")  # 替换原来的文件  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()  #删除替换文件  os.remove('commodit_update') elif choose =='2':  # 添加商品  f = open('commodit', 'a+', encoding='utf-8')  pricename = input("请输入商品名:")  while True:   price = input("请输入商品价格:")   if price.isdigit():    f.writelines('%s %s/n' % (pricename, price))    break   else:    print('输入错误请重新输入!')    continue  f.close()  continue elif choose =='q':  break else:  print("输入错误请重新输入")  continue

# 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("请输入你的现金:")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)  #判断用户要输入  user_choice = input("请选择要买什啥>>>:")  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: #买得起     shopping_list.append(p_item)     salary -=p_item[1]     print("加入 %s 购物车你的余额是/033[31;1m%s/033[0mRMB" %(p_item,salary))    else:     print("/033[32;1m 你的余额只剩[%s]RMB啦，还买个毛线/033[0m " %salary)   else:    print("/033[41;1m您输入的商品不存在，请重新输入!/033[0m")  elif user_choice == 'q':   print("----shopping_list----")   for p in shopping_list:    print(p)   print("你的余额:/033[31;1m%s/033[0mRMB" %salary)   #简单的余额记录   f = open('salary','w+',encoding='utf-8')   f.writelines(str(salary))   f.close   exit()  else:   print("错误选项")