作业：购物商城
商品展示，价格
买，加入购物车
付款，钱不够
具体实现了如下功能：
1、可购买的商品信息显示
2、显示购物车内的商品信息、数量、总金额
3、购物车内的商品数量进行增加、减少和商品的删除
4、用户余额的充值
5、用户购买完成进行结账，将最终余额回写到用户文件中。
一、用户文件说明：
kevin 123 50000 sky 123 54000 mobi 123 80000
其中第一列为用户名，第二列为密码，第三列为帐户余额。
二、流程图如下：
import sys,os,getpass,time def input_handle(s): '''用户输入字符数字转化为数字''' if s.isdigit(): #判断用户输入是否是字符数字 s = int(s) #是的话就进行转换 return s def framework(user="",init_money='',now_money='',recharge_money='',value=''): '''架构函数，展示用户的基本信息''' os.system("clear") init_money = int(init_money) now_money = int(now_money) recharge_money = int(recharge_money) message = ''' ******************************************************************************* 033[32;1m欢迎来到小猪猪购物商城033[0m ******************************************************************************* 会员：%s 金额：%d 当前余额：%d 充值金额：%d 购物车:%d ''' %(user,init_money,now_money,recharge_money,value) print(message) def goods_list_show(my_dict): '''商品展示模块，用于展示商品''' local_dict = {} '''对商品列表进行遍历并加上数字编号''' i = 1 print("商品列表：") print("=================================================================================================") print("%-5s %-15s %-10s %-10s %-10s" %("编号","商品名称","商品价格(元)","商品总数量(个)","商品剩余数量(个)")) for k in my_dict.keys(): v = my_dict[k] if type(v) == dict: print("%-5s %-20s %-15d %-18d %-10d" %(i,k,v['price'],v['num'],v['sum'])) local_dict[i] = [k,v["price"],v['num'],v['sum']] i += 1 print("=================================================================================================") return local_dict def cart_goods_show(show_dict): '''显示购物车商品,并加上数字编号''' show_all_sum = 0 show_all_num = 0 '''对商品列表进行遍历并加上数字编号''' message = ('编号',"商品名称","商品价格(元)","商品总数量(个)","购买数量(个)","购买金额(元)") print("%-5s %-20s %-10s %-10s %-10s %-10s" %message) for k in show_dict: v = show_dict[k] if type(v) is dict: print("%-5s %-10s %-10d %-10d %-10d %-10d" %(k,v[0],v[1],v[2],v[3],v[4])) show_all_num += v[4] show_all_num += 1 print("请确认你购买的商品，总金额：%d元"%(show_all_sum)) return (show_all_sum,show_all_num) def cart_goods_modify(modify_dict,modify_goods_dict): '''购物车商品修改列表''' a_flag = 1 while a_flag: index = input("请输入商品编号|完成修改(q):" %modify_dict[index][2]) if len(index) != 0: index = input_handle(index) if index == "q": break elif index in modify_dict: b_flag = 1 name = modify_dict[index][0] while b_flag: num = input("请输入新的商品数量(最大值为%d)|完成修改(q)：" %modify_dict[index][2]) if len(num) != 0: num = input_handle(num) if num == 'q': break elif num == 0: modify_goods_dict[name]['num'] = modify_dict[index][2] del modify_dict[index] b_flag = 0 elif num > 0 and num <= modify_dict[index][2]: modify_dict[index][3] = num modify_dict[index][4] = modify_dict[index][1] * num modify_goods_dict[name]['num'] = modify_dict[index][2] - num b_flag = 0 else: pass else: pass return (modify_dict,modify_goods_dict) def shopping_cart_show(my_cart,my_goods_dict): '''购物车展示''' print("欢迎来到你的购物车".center(80,"#")) goods_all_sum = 0 goods_all_num = 0 if my_cart: '''调用购物车商品列表函数,并返回商品总金额和总数量''' (goods_all_sum,goods_all_num) = cart_goods_show(my_cart) choice = input("请进行如下操作：修改记录(c)|继续购物(!c)") if choice == "c": (my_shop_cart,my_goods_dict) = cart_goods_modify(my_cart,my_goods_dict) (goods_all_sum,goods_all_num) = cart_goods_show(my_cart) else: pass else: print("您当前的购物车为空".center(80,"#")) time.sleep(2) return (goods_all_sum,goods_all_num,my_goods_dict) def balance_recharge(recharge_init_balance,recharge_now_balance,recharge_money): recharge_flag = 1 while recharge_flag: recharge_num = input("请输入充值金额|返回(b)|退出(q)：") if len(recharge_num) != 0: recharge_num = input_handle(recharge_num) if recharge_num == "q": sys.exit(0) elif recharge_num == 'b': break elif type(recharge_flag) is int and recharge_num > 0: recharge_init_balance += recharge_num recharge_now_balance += recharge_num recharge_money += recharge_num recharge_flag = 0 print("充值成功，请查收".center(80,"#")) else: pass return (recharge_init_balance,recharge_now_balance,recharge_money) def user_billing(billing_list,my_cart,billing_balance): '''结帐模块''' print("欢迎来到结帐模块".center(80,"#")) if my_cart: '''调用购物车商品列表函数''' cart_goods_show(my_cart) billing_flag = input("请确认是否商品结算(y|n)：") if billing_flag == "y": billing_file = open("info.txt",'w') for user_info in billing_list: billing_file.writelines(user_info) billing_file.close() sys.exit("结帐成功，您当前余额：%d".center(80,"#") %billing_balance) else: print("退出结算菜单，继续购物".center(80,"#")) time.sleep(2) else: print("您当前的购物车为空，无需结算！") time.sleep(2) '''主程序开始''' if __name__ == "__main__": goods_list = { 'iphone6': {'price':6000,'num':10,'sum':10}, 'ipad': {'price':3000,'num':20,'sum':20}, 'mi4': {'price':2000,'num':43,'sum':43}, 'huawei6_plus': {'price':1999,'num':8,'sum':8}, } i = 0 while i < 3: #只要用户登录不超过3次就不断循环 username = input("请输入用户名：") password = input("请输入密码：") user_file = open("info.txt",'r') user_list = user_file.readlines() user_file.close() for user_line in user_list: '''分别获取当前账号、密码和余额信息''' user,passwd,init_balance = user_line.strip(' ').split() init_balance = int(init_balance) now_balance = init_balance my_goods_sum = 0 if user == username and password == passwd: user_shopping_cart = {} user_shopping_cart_count = 0 recharge_value = 0 line_num = user_list.index(user_line) first_flag = 1 while first_flag: '''调用框架函数输出用户信息''' framework(username,init_balance,now_balance,recharge_value,user_shopping_cart_count) goods_output_dict = goods_list_show(goods_list) #输出商品信息 goods_index = input("请选择菜单：输入商品编号 | 购物车(c) | 余额充值(r) | 结账(b) | 退出(q) :") if len(goods_index) != 0: goods_index = input_handle(goods_index) if goods_index == 'q': sys.exit(0) elif goods_index == 'c': '''调用购物车显示函数，并返回购物车商品总金额''' (my_goods_sum,user_shopping_cart_count,goods_list) = shopping_cart_show(user_shopping_cart,goods_list) now_balance = init_balance - my_goods_sum if now_balance < 0: print("您的余额不足，请及时充值！") time.sleep(2) elif goods_index == 'r': (init_balance,now_balance,recharge_value) = balance_recharge(init_balance,now_balance,recharge_value) elif goods_index == 'b': '''更新用户的余额''' user_list[line_num] = user + ' ' + passwd + ' ' + repr(now_balance) + ' ' user_billing(user_list,user_shopping_cart,now_balance) elif goods_index in goods_output_dict: '''取出goods_index商品列表信息并进行赋值和展示''' (goods_name,goods_price,goods_num) = (goods_output_dict[goods_index][0],goods_output_dict[goods_index][1],goods_output_dict[goods_index][2]) print('【 编号：%-5d 名称：%-15s 价格：%-5d（元） 数量：%-5d（个）】' % (goods_index, goods_name, goods_price, goods_num)) second_flag = 1 while second_flag: buy_num = input('请输入购买商品个数(最大值为%d) | 返回(b) | 退出(q): ' % goods_num) if len(buy_num) != 0: buy_num = input_handle(buy_num) if buy_num == 'q': sys.exit(0) elif buy_num == 'b': break elif type(buy_num) is int and buy_num > 0 and buy_num <= goods_num: my_goods_sum = goods_price * buy_num if my_goods_sum <= now_balance: print('购买商品 %s 总价格为 : %d' % (goods_name, my_goods_sum)) add_flag = input("请确认是否加入购物车（y | n)：") if add_flag == "y": '''判断购物车不存在该商品''' if goods_index not in user_shopping_cart: user_shopping_cart_count += 1 '''购物车商品数量加一''' user_shopping_cart[goods_index] = [goods_name,goods_price,goods_num,buy_num,my_goods_sum] else: user_shopping_cart[goods_index][3] += buy_num user_shopping_cart[goods_index][4] += my_goods_sum now_balance -= my_goods_sum goods_list[goods_name]['num'] -= buy_num second_flag = 0 else: break else: print("您的余额不足，请充值或重新选择，谢谢！") time.sleep(2) else: pass else: pass else: if i != 2: print('用户或密码错误，请重新输入，还有 %d 次机会' % (2 - i)) i += 1 else: sys.exit('用户或密码输入错误超过三次，退出系统,欢迎下次光临')
上述代码不难，难的是思路，思路很重要，要知道如何一步一步去操作，用的也都是我们常用的知识，其实归根揭底我们写程序，大部分使用的都是字符串，字典，列表的功能。还有一些模块之类的。在写程序的过程中，思路显得尤为重要。知道了思路，就考虑如何使用代码去实现，上面程序中学到了如下知识点；
1、输出格式对其：print("%-5s %-15s %-10s %-10s %-10s" %("编号","商品名称","商品价格(元)","商品总数量(个)","商品剩余数量(个)"))，上面代码能够实现对其格式的功能，让我们输出的字符串格式统一，比如上述代码中，编号左对齐5个字符，商品名称左对齐15个字符等等；
2、str.center()的使用，如print("欢迎来到你的购物车".center(80,"#"))；