#compile
f = open("函数递归.py")
data =compile(f.read(),'','exec')
exec(data)
#print
msg = "又回到最初的起点"
f = open("tofile","w")
print(msg,"记忆中你青涩的脸",sep="|",end="",file=f)
# #slice
# a = range(20)
# pattern = slice(3,8,2)
# for i in a[pattern]: #等于a[3:8:2]
# print(i)
#
#
#memoryview
#usage:
#>>> memoryview(b'abcd')
#<memory at 0x104069648>
#在进行切片并赋值数据时，不需要重新copy原列表数据，可以直接映射原数据内存，
import time
for n in (100000, 200000, 300000, 400000):
data = b'x'*n
start = time.time()
b = data
while b:
b = b[1:]
print('bytes', n, time.time()-start)
for n in (100000, 200000, 300000, 400000):
data = b'x'*n
start = time.time()
b = memoryview(data)
while b:
b = b[1:]
print('memoryview', n, time.time()-start)
几个内置方法用法提醒
练习题
修改个人信息程序
在一个文件里存多个人的个人信息，如以下
username password age position department
alex abc123 24 Engineer IT
rain df2@432 25 Teacher Teching
....
1.输入用户名密码，正确后登录系统 ，打印
1. 修改个人信息
2. 打印个人信息
3. 修改密码
2.每个选项写一个方法
3.登录时输错3次退出程序
练习题答案
def print_personal_info(account_dic,username):
"""
print user info
:param account_dic: all account's data
:param username: username
:return: None
"""
person_data = account_dic[username]
info = '''
------------------
Name: %s
Age : %s
Job : %s
Dept: %s
Phone: %s
------------------
''' %(person_data[1],
person_data[2],
person_data[3],
person_data[4],
person_data[5],
)
print(info)
def save_back_to_file(account_dic):
"""
把account dic 转成字符串格式 ，写回文件
:param account_dic:
:return:
"""
f.seek(0) #回到文件头
f.truncate() #清空原文件
for k in account_dic:
row = ",".join(account_dic[k])
f.write("%s\n"%row)
f.flush()
def change_personal_info(account_dic,username):
"""
change user info ,思路如下
1. 把这个人的每个信息打印出来， 让其选择改哪个字段，用户选择了的数字，正好是字段的索引，这样直接 把字段找出来改掉就可以了
2. 改完后，还要把这个新数据重新写回到account.txt，由于改完后的新数据 是dict类型，还需把dict转成字符串后，再写回硬盘
:param account_dic: all account's data
:param username: username
:return: None
"""
person_data = account_dic[username]
print("person data:",person_data)
column_names = ['Username','Password','Name','Age','Job','Dept','Phone']
for index,k in enumerate(person_data):
if index >1: #0 is username and 1 is password
print("%s. %s: %s" %( index, column_names[index],k) )
choice = input("[select column id to change]:").strip()
if choice.isdigit():
choice = int(choice)
if choice > 0 and choice < len(person_data): #index不能超出列表长度边界
column_data = person_data[choice] #拿到要修改的数据
print("current value>:",column_data)
new_val = input("new value>:").strip()
if new_val:#不为空
person_data[choice] = new_val
print(person_data)
save_back_to_file(account_dic) #改完写回文件
else:
print("不能为空。。。")
account_file = "account.txt"
f = open(account_file,"r+")
raw_data = f.readlines()
accounts = {}
#把账户数据从文件里读书来，变成dict,这样后面就好查询了
for line in raw_data:
line = line.strip()
if not line.startswith("#"):
items = line.split(",")
accounts[items[0]] = items
menu = '''
1. 打印个人信息
2. 修改个人信息
3. 修改密码
'''
count = 0
while count <3:
username = input("Username:").strip()
password = input("Password:").strip()
if username in accounts:
if password == accounts[username][1]: #
print("welcome %s ".center(50,'-') % username )
while True: #使用户可以一直停留在这一层
print(menu)
user_choice = input(">>>").strip()
if user_choice.isdigit():
user_choice = int(user_choice)
if user_choice == 1:
print_personal_info(accounts,username)
elif user_choice == 2:
change_personal_info(accounts,username)
elif user_choice == 'q':
exit("bye.")
else:
print("Wrong username or password!")
else:
print("Username does not exist.")
count += 1
else:
print("Too many attempts.")
