为了以后更好更快速的复习，此博客记录我对作业的总结。对于基础作业，我认为最重要的是过程，至于实现是不是完美，代码是不是完美，虽然重要，但是作业过程中，用到的知识点是值得总结和整理的。

一.购物车：

1. 商品信息- 数量、单价、名称  
2. 用户信息- 帐号、密码、余额  
3. 用户可充值  
4. 购物历史信息  
5. 允许用户多次购买，每次可购买多件  
6. 余额不足时进行提醒  
7. 用户退出时 ，输出当次购物信息  
8. 用户下次登陆时可查看购物历史  
9. 商品列表分级显示

思路：

1.此作业是day1作业的结合体；

2.用户登录是否首次，分为新用户和旧用户；

3.旧用户查看是否有购物历史；

4.购买时可输入购买数量；

5.余额大于等于购买商品花费则购买成功，购买成功记录购买信息；

6.余额小于购买商品花费则提示充值，要求输入充值金额；

6.购物车自动整理购物商品与花费；

7.可随时查看购物车；

基本流程图：

代码：

cat shopping_cart.py

#!/usr/bin/env python
# _*_coding:utf-8_*_
'''* Created on 2016/10/18 22:01.* @author: Chinge_Yang.
'''
import os
import getpass
import datetime
menu = {"Mobile phone": [("Iphone7", 6188),("Iphone7 plus", 7888),("Xiaomi5", 2888)],"Car": [("Audi Q5", 490000),("Ferrari 488", 4888888)],"Drink": [("Milk", 59),("Coffee", 30),("Tea", 311)]
}
user_file = "user.txt"
shopping_log = "shopping.log"
money = 0   #初始金额
all_cost = 0
shopping_cart = {}
exit_user_flag = False
exit_flag = False
exsit_flag = False
if not os.path.exists(user_file):f = open(user_file,'w')f.close()
if not os.path.exists(shopping_log):f = open(shopping_log,'w')f.close()
def show_shopping_cart ():    #显示购物车，更新用户信息，exit前使用#显示购物车信息print("You purchased products as below".center(50,"*"))print("%-20s %-15s %-10s %-20s" %("Goods","Price","Number","Cost"))for key in shopping_cart:p_name = key[0]p_price = int(key[1])p_number = int(shopping_cart[key])print("%-20s %-15s %-10s \033[32;1m%-20s\033[0m" %(p_name,p_price,p_number,p_price*p_number))print("End".center(50,"*"))print("%-20s %-15s %-10s \033[32;1m%-20s\033[0m" %("You total cost:","","",all_cost))print("Your balance is [\033[32;1m%s\033[0m]" % money)if new_user is True:# 将新用户信息写入到用户文件中file = open(user_file, "a")file.write("%s %s %s\n" % (user_name, user_passwd, money))  # 用户、密码、金钱存入用户文件file.close()else:if old_money != money:  #充值或买了东西# 将旧用户信息更新到用户文件中old_user_info = "%s %s %s" % (user_name, user_passwd, old_money)new_user_info = "%s %s %s" % (user_name, user_passwd, money)with open(user_file) as file:info = file.read()new_info = info.replace(old_user_info,new_user_info)with open(user_file,"w") as file:file.write(new_info)
while exit_user_flag is not True:#输入用户密码user_name = input("Please input your name:").strip()#user_passwd = input("Please input your password:").strip()user_passwd = getpass.getpass("\033[1;33mPlease input your password:\033[0m")if user_name == '' or user_passwd == '':continueelif ' ' in user_name:print("\033[31;1mNot allowed to contain spaces!\033[0m")continue#查看是否存在于用户数据库user_check = open(user_file)for l in user_check:l = l.split()user = l[0]passwd = l[1]if user_name == user:   #老用户new_user = False    #标记为老用户money = int(l[2])   #记录用户余额old_money = money   #旧余额if not passwd == user_passwd:print ("\033[1;31mYour password is error!\033[0m".center(50,"*"))else:print ("\033[1;31mWelcome to go shopping!\033[0m".center(50,"-"))exit_user_flag = Truebreakelse:new_user = True #标记为新用户exit_user_flag = Trueuser_check.close()  #关闭
if not new_user:    #旧用户#读取购物历史，判断是否有此用户记录file = open(shopping_log)for line in file:line = line.split()line_user = line[0]if line_user == user_name:  #存在记录exsit_flag = Truebreak   #跳出检测file.close()if exsit_flag is True:   #内容不为空#只有输入y或者yes才读取显示购物历史，否则不显示print("Input \033[1;33m[y|yes]\033[0m to view your purchase history,\033[1;33m[others]\033[0m means not.")see_history = input("Please input:").strip()if see_history == "y" or see_history == "yes":# 显示用户购物历史# output = os.system("grep %s %s" %(user_name,shopping_log))# print(output.read())print("User %s shopping history:" % user_name)print("%-20s %-15s %10s %20s" %("Username","datetime","Number","Goods"))file = open(shopping_log)for line in file:line = line.split("\t")line_user = line[0]if line_user == user_name:  #存在记录print("%-10s %-15s %10s %20s" % (line[0],line[1],line[2],line[3].strip()))file.close()else:print("You are not to view your purchase history!")print("-".center(50,"-"))
one_layer_list = [] #一级菜单
while True:while True:#打印各类菜单print("Species list".center(50,"-"))for index, item in enumerate(menu):print("\033[32;1m%d\033[0m --> %s" % (index, item))one_layer_list.append(item)print("End".center(50,"-"))print("[q|b] to quit")once_choice = input("Input your choice:").strip()if once_choice.isdigit():   #输入数字once_choice = int(once_choice)if 0 <= once_choice < len(menu):    #输入正确数字print("---->Enter \033[32;1m%s\033[0m" %(one_layer_list[once_choice]))two_layer_list = menu[one_layer_list[once_choice]]exit_flag = False   #重新进入二级商品菜单break   #跳出循环，往下走else:print("\033[31;1mNumber out of range, please enter again!\033[0m")else:if once_choice == "b" or once_choice == "back" or once_choice == "q" or once_choice == "quit":show_shopping_cart()exit("Bye,thanks!".center(50,"#"))print("\033[31;1mPlease enter the Numbers!\033[0m")while exit_flag is not True:#显示二级商品菜单print("Product list".center(50,'-'))for item in enumerate(two_layer_list):index = item[0]p_name = item[1][0]p_price = item[1][1]print("%s.%-20s %-20s" %(index,p_name,p_price))print("End".center(50,'-'))print("[q|quit] to quit;[b|back] to back")user_choice = input("Please choice the product:").strip()if user_choice.isdigit():   #输入数字user_choice = int(user_choice)if 0 <= user_choice < len(two_layer_list):product_number = input("Please input the number of product:").strip()   #输入个数if product_number.isdigit():product_number = int(product_number)else:continue    #重新选择商品和个数p_item = two_layer_list[user_choice]p_name = p_item[0]  #商品名p_price = int(p_item[1])    #商品价格new_added = {}if p_price*product_number <= money: #能付款，表示购买成功new_added = {p_item:product_number}#整理购物车个数显示总数for k, v in new_added.items():if k in shopping_cart.keys():shopping_cart[k] += velse:shopping_cart[k] = vmoney -= p_price * product_numberall_cost += p_price * product_numberprint("Added [\033[32;1m%d\033[0m] [\033[32;1m%s\033[0m] into shopping cart,""your balance is [\033[32;1m%s\033[0m]" % (product_number,p_name,money))with open(shopping_log,"a") as file:log = "%s\t\"%s\"\t%d\t\"%s\"\n" %(user_name,datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S'),product_number,p_name)shopping_history = file.write(log)else:#钱不够时，提示充值print("Your balance is [\033[31;1m%s\033[0m],cannot afford this.." % money)while True:user_charge = input("Do you want to charge more money?[\033[32;1my|n|b]\033[0m").strip()if user_charge == "y" or user_charge == "yes":charge_number = input("Please input your top-up amount:").strip()if charge_number.isdigit():charge_number = int(charge_number)money += charge_number  #充值成功print("Your balance is [\033[32;1m%s\033[0m]" % money)else:print("Your input is not number!")continuebreakelif user_charge == "n" or user_charge == "no" or user_charge == "b" or user_charge == "back":break   #放弃充值else:if user_choice == "q" or user_choice == "quit":show_shopping_cart()exit("Bye,thanks!".center(50,"#"))elif user_choice == "c" or user_choice == "check":print("You purchased products as below".center(50,"*"))print("%-20s %-15s %-10s %-20s" %("Goods","Price","Number","Cost"))for key in shopping_cart:p_name = key[0]p_price = int(key[1])p_number = int(shopping_cart[key])print("%-20s %-15s %-10s \033[32;1m%-20s\033[0m" %(p_name,p_price,p_number,p_price*p_number))print("End".center(50,"*"))print("%-20s %-15s %-10s \033[32;1m%-20s\033[0m" %("You total cost:","","",all_cost))print("Your balance is [\033[32;1m%s\033[0m]" % money)elif user_choice == "b" or user_choice == "back":exit_flag = Trueelse:print("Your input is error!")

总结：

1.用到的基础知识点不少，不仅复习了day1知识，更灵活运用了列表、字典、元组等；

2.购物车还可以再完美，比如增加商品列表固定排序（如果使用json，我不知道怎么用），增加余额充值接口（使用信用卡）等；

3.对于复杂一些的需求，层次要分明，条理清晰，才能使自己逻辑思维鲜明；

本文出自 “ygqygq2” 博客，谢绝转载！