PYTHON之文件操作

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()