考前复习：
path 有4个：path.exists path.isdir path.isfile path.join
dir 有3个：mkdir rmdir listdir
还有一个remove用于删除文件
路径用 \\
打开：with open(‘文件名’,’r w a rb wb’,encoding=’utf-8 gbk’) as file
读取：readlines readline read(size)
写入：write writelines(list)
移动游标：
seek(位置下标)
seek(delta,2) seek(delta,1) 分别表示末尾和当前位置，用rb

创建文件：

import os
name=r'empty_directory'
print(os.getcwd())
if(os.path.exists(name)):
    print('please quit')
else:
    os.mkdir(name)

读取文件：

file=open('lzp.txt','r')
content=file.read()
print(content)
print(file.read())
file.seek(0)
print(file.read())
file.seek(0)
lines=file.readlines()
print(len(lines))
file.seek(0)
count=0
for line in file:
    print(count,line)
    print(type(count),type(line))
file.close()

给图片加密：

import os
file_path=r"docs/image.jpg"
para=10
if os.path.exists(file_path):
    print("File exists!")
    with open(file_path,'rb') as file:
        content=bytearray(file.read())
        print(type(content))
        original_content=content[:para]
        content[:para]=b'\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF'
    with open(file_path,'wb') as file:
        file.write(content)
    with open(r'docs/key.dat','wb') as file:
        file.write(original_content)
else:
    print("File not exists!")

给图片解密：

import os
file_path=r"docs/image.jpg"
para=10
if os.path.exists(file_path):
    print("File exists!")
    with open(file_path,'rb') as file:
        content=bytearray(file.read())
    with open(r'docs/key.dat','rb') as file:
        original_content=bytearray(file.read())
    with open(file_path,'wb') as file:
        content[:para]=original_content
        file.write(content)
else:
    print("File not exists!")

在文件中间写：

import os
with open('lzp.txt','r+') as file:
    file.seek(3)
    file.write('gg')
with open('lzp.txt','r') as file:
    print(file.read())