一、文件处理实战之购物车系统
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用户名和密码存放于文件中，格式为：nick|nick123
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启动程序后，先登录，登录成功则让用户输入工资,然后打印商品列表，失败则重新登录，超过三次则退出程序
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允许用户根据商品编号购买商品
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用户选择商品后，检测余额是否够，够就直接扣款，不够就提醒
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可随时退出，退出时，打印已购买商品和余额
import os
product_list = [
['Iphone7', 5800],
['Coffee', 30],
['疙瘩汤', 10],
['Python Book', 99],
['Bike', 199],
['ViVo X9', 2499],
]
shopping_cart = {}
current_userinfo = []
db_file = r'db.txt'
while True:
print('''
登陆
注册
购物
''')
choice = input('>>: ').strip()
if choice == '1':
#1、登陆
tag = True
count = 0
while tag:
if count == 3:
print('尝试次数过多，退出。。。')
break
uname = input('用户名：').strip()
pwd = input('密码：').strip()
with open(db_file, 'r', encoding='utf-8') as f:
for line in f:
line = line.strip('
')
user_info = line.split(',')
uname_of_db = user_info[0]
pwd_of_db = user_info[1]
balance_of_db = int(user_info[2])
if uname == uname_of_db and pwd == pwd_of_db:
print('登陆成功')
# 登陆成功则将用户名和余额添加到列表
current_userinfo = [uname_of_db, balance_of_db]
print('用户信息为：', current_userinfo)
tag = False
break
else:
print('用户名或密码错误')
count += 1
elif choice == '2':
uname = input('请输入用户名：').strip()
while True:
pwd1 = input('请输入密码：').strip()
pwd2 = input('再次确认密码：').strip()
if pwd2 == pwd1:
break
else:
print('两次输入密码不一致，请重新输入！！!')
balance = input('请输入充值金额：').strip()
with open(db_file, 'a', encoding='utf-8') as f:
f.write('%s,%s,%s
' % (uname, pwd1, balance))
elif choice == '3':
if len(current_userinfo) == 0:
print('请先登陆...')
else:
#登陆成功后，开始购物
uname_of_db = current_userinfo[0]
balance_of_db = current_userinfo[1]
print('尊敬的用户[%s] 您的余额为[%s],祝您购物愉快' % (uname_of_db, balance_of_db))
tag = True
while tag:
for index, product in enumerate(product_list):
print(index, product)
choice = input('输入商品编号购物，输入q退出>>: ').strip()
if choice.isdigit():
choice = int(choice)
if choice < 0 or choice >= len(product_list): continue
pname = product_list[choice][0]
pprice = product_list[choice][1]
if balance_of_db > pprice:
if pname in shopping_cart: # 原来已经购买过
shopping_cart[pname]['count'] += 1
else:
shopping_cart[pname] = {
'pprice': pprice,
'count': 1
}
balance_of_db -= pprice # 扣钱
current_userinfo[1] = balance_of_db # 更新用户余额
print(
"Added product " + pname +
" into shopping cart,[42;1myour current balance "
+ str(balance_of_db))
else:
print("买不起，穷逼! 产品价格是{price},你还差{lack_price}".format(
price=pprice, lack_price=(pprice - balance_of_db)))
print(shopping_cart)
elif choice == 'q':
print("""
---------------------------------已购买商品列表---------------------------------
id 商品 数量 单价 总价
""")
total_cost = 0
for i, key in enumerate(shopping_cart):
print('%22s%18s%18s%18s%18s' %
(i, key, shopping_cart[key]['count'],
shopping_cart[key]['pprice'],
shopping_cart[key]['pprice'] *
shopping_cart[key]['count']))
total_cost += shopping_cart[key][
'pprice'] * shopping_cart[key]['count']
print("""
您的总花费为: %s
您的余额为: %s
---------------------------------end---------------------------------
""" % (total_cost, balance_of_db))
while tag:
inp = input('确认购买(yes/no?)>>: ').strip()
if inp not in ['Y', 'N', 'y', 'n', 'yes', 'no']:
continue
if inp in ['Y', 'y', 'yes']:
# 将余额写入文件
src_file = db_file
dst_file = r'%s.swap' % db_file
with open(src_file,'r',encoding='utf-8') as read_f,
open(dst_file,'w',encoding='utf-8') as write_f:
for line in read_f:
if line.startswith(uname_of_db):
l = line.strip('
').split(',')
l[-1] = str(balance_of_db)
line = ','.join(l) + '
'
write_f.write(line)
os.remove(src_file)
os.rename(dst_file, src_file)
print('购买成功，请耐心等待发货')
shopping_cart = {}
current_userinfo = []
tag = False
else:
print('输入非法')
elif choice == 'q':
break
else:
print('非法操作')
登陆
注册
购物
>>: 2
请输入用户名：nick
请输入密码：123
再次确认密码：123
请输入充值金额：10000
登陆
注册
购物
>>: 1
用户名：nick
密码：123
登陆成功
用户信息为： ['nick', 10000]
登陆
注册
购物
>>: 3
尊敬的用户[nick] 您的余额为[10000],祝您购物愉快
0 ['Iphone7', 5800]
1 ['Coffee', 30]
2 ['疙瘩汤', 10]
3 ['Python Book', 99]
4 ['Bike', 199]
5 ['ViVo X9', 2499]
输入商品编号购物，输入q退出>>: 0
Added product Iphone7 into shopping cart,[42;1myour current balance 4200
{'Iphone7': {'pprice': 5800, 'count': 1}}
0 ['Iphone7', 5800]
1 ['Coffee', 30]
2 ['疙瘩汤', 10]
3 ['Python Book', 99]
4 ['Bike', 199]
5 ['ViVo X9', 2499]
输入商品编号购物，输入q退出>>: 1
Added product Coffee into shopping cart,[42;1myour current balance 4170
{'Iphone7': {'pprice': 5800, 'count': 1}, 'Coffee': {'pprice': 30, 'count': 1}}
0 ['Iphone7', 5800]
1 ['Coffee', 30]
2 ['疙瘩汤', 10]
3 ['Python Book', 99]
4 ['Bike', 199]
5 ['ViVo X9', 2499]
输入商品编号购物，输入q退出>>: q
---------------------------------已购买商品列表---------------------------------
id 商品 数量 单价 总价
0 Iphone7 1 5800 5800
1 Coffee 1 30 30
您的总花费为: 5830
您的余额为: 4170
---------------------------------end---------------------------------
确认购买(yes/no?)>>: yes
购买成功，请耐心等待发货
登陆
注册
购物
>>: q