目此文档分享如果python对文件的操作
python2.*打开文件：
file_obj = file("文件路径","模式")
file_obj = open("文件路径","模式")
Python3.*打开文件：
file_obj = open("文件路径","模式")
打开文件的模式有：
r：以只读方式打开文件
w：打开一个文件只用于写入。如果该文件已存在则将其覆盖。如果该文件不存在，创建新文件
a：打开一个文件用于追加。如果该文件已存在，文件指针将会放在文件结尾。
w+：打开一个文件用于读写。如果该文件已存在则将期覆盖。如果该文件不存在，创建新文件。
例：
#写文件
'''
f = open("text.log","w")
f.write("this is the first line! ")
f.write("this is the 3 lien! ")
f.write("this is the 4 lien! ")
f.close()
#读文件
f = open("text.log","r")
#print(f.read())
print(f.readlines())
f.close()
#追加文件
f = open("text.log","a")
f.write("6 ")
f.write("7 ")
f.close()
'''
#读写文件
f = open("text.log","w+")
f.write("new line ")
print(f.read())
f.close()
实例：
------说明----
文件介绍:
start.py 为程序启动主文件
marry.py 为验证用户是否存在文件
keys.py 为是否解除用户锁定文件
info.txt 为锁用户的文件库
1运行程序start.py
2输入用户名和密码(输错密码3次会被锁)
username:tale password:123456
3用户验证
1)用户是否被锁
2)是否要解锁该用户
3)验证输入的用户名和密码是否正确
4)解锁用户需要输入正确的用户名和密码
4三级菜单
1)产品列表
2)当单选中产品,会显示产品价格信息
start.py代码
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from marry import file_bool
file_name = open("info.txt","r+")
file_list = file_name.readlines()
userinfos = ["tale","123456","10000","1"]
Shopping = {"Commodity":["1:Cup","2:Young lady","3:AV"]}
Price = {"1":"10","2":"888","3":"666"}
username = userinfos[0]
passwords = userinfos[1]
stop = int(userinfos[3])
#user login
for i in range(3):
user = raw_input("input username:").strip()
pa = raw_input("input password:")
#判断用户是否存在
if user == userinfos[0]:
pass
else:
print("not username!")
exit()
#判断用户是否已被锁定
file_bool(user,pa)
if user == username and pa == passwords:
print("welcome %s login!" % user)
break
else:
print("password or username err!")
stop += 1
userinfos[3] = stop
if userinfos[3] == 4:
print("The user is locked.")
lst_info = str(userinfos)
values_list = "".join(lst_info)
file_name.write(values_list+" ")
file_name.close()
exit()
else:
pass
#三级菜单
while True:
for comm,valus in Shopping.items():
print(valus)
Shopgo =raw_input("是否要购买 n/y:")
if Shopgo == "n" or Shopgo == "N":
exit()
elif Shopgo == "y" or Shopgo == "Y":
continue
else:
print("不按规定输入,用户强制退出!")
exit()
print("Price tabulation")
for key,sp in Price.items():
print("ID:%s Price:%s$" % (key,sp))
IDcode = raw_input("Please input ID:")
if IDcode == "1":
print("Success purchase commodity:Cup")
elif IDcode == "2":
print("Success purchase commodity:Young lady")
elif IDcode == "3":
print("Success purchase commodity:AV")
else:
print("Not this commodity!")
exit()
marry.py代码
#!/usr/bin/env python
# -*- coding:utf-8 -*-
from keys import keyinfo
def file_bool(users,passinfo):
file_name = open("info.txt","r+")
file_list = file_name.readlines()
for ele in file_list:
line = ele.strip()
values_list = line.split(',')
last_value = str(values_list[-1])
last_user = str(values_list[0])
last_pass = str(values_list[1])
strip_pass = last_pass.strip(" ")
strip_pass2 = strip_pass.strip("'")
strip1 = last_user.strip("[")
strip2 = strip1.strip("'")
if strip2 == users and strip_pass2 == passinfo:
if last_value[1] >= 4 and strip2 == users:
keys = raw_input("是否要解锁%s用户:Y/N" % users)
if keys == "Y" or keys == "y":
keyinfo()
print("用户已解锁!")
exit()
elif keys == "N" or keys == "n":
print("程序退出!")
exit()
else:
print("请输入正确选项!")
exit()
else:
pass
file_name.close()
else:
print("用户被锁,程序退出.请输入正确的用户名和密码解锁!")
exit()
keys.py代码
#!/usr/bin/evn python
def keyinfo():
file_name = open("info.txt","r+")
file_name.truncate()
file_name.close()