python_文件操作

一、
r+模式读写，读完之后再写入就会追加内容
不读直接写入将会从头开始覆盖内容
f = open('01.txt',mode='r+',encoding='utf-8')
data = f.read()
print(data)
f.write('秋名山
今晚洗车
一路向北')
f.write('hello world')
f.close()

read一次性读完文件
with open('01.txt',encoding='utf-8') as f:
data = f.read()
print(data)

按指定字节字符读取
f = open('01.txt',encoding='utf-8')
f = open('01.txt','rb')
f.seek(10)
print(f.read(4))
f.close()

f = open('01.txt',encoding='utf-8')
读取一行
print(f.readline())
按行读取，返回一个list
print(f.readlines())
f.close()

for循环读取文件
f = open('01.txt',encoding='utf-8')
for line in f:
　　print(line.strip())
f.close()

r+ rb r+b　　模式
f = open('01.txt','r+',encoding='utf-8')
print(f.read())
f.write('666')
f.close()

f = open('01.txt','rb')
print(f.read())
f.close()

f = open('01.txt','r+b')
f.read()
f.write('哇喔1234'.encode('utf-8'))
f.close() 

w w+ wb w+b　　 模式
f = open('02.txt','w',encoding='utf-8')
f.write('好久不见')
f.close()

f = open('02.txt','w+',encoding='utf-8')
f.write('哈哈')
f.seek(0)
print(f.read())
f.close()

f = open('02.txt','wb')
f.write('你好啊'.encode('utf-8'))
f.close()

f = open('02.txt','w+b')
print(f.read())
f.write('好久不'.encode('utf-8'))
f.seek(0)
print(f.read())
f.close()

a a+ ab a+b　　模式
f = open('02.txt','a',encoding='utf-8')
f.write('见你')
f.close()

f = open('02.txt','a+',encoding='utf-8')
f.write('aa')
f.seek(0)
print(f.read())
f.close()

f = open('02.txt','ab')
f.write('哈'.encode('utf-8'))
f.close()

f = open('02.txt','a+b',)
f.seek(0)
print(f.read())
f.close()

 文件操作其它方法
 readable  writeable   是否可读，可写
 f = open('02.txt','r+',encoding='utf-8')
 print(f.readable())
 print(f.writable())
 f.close()

 调整光标位置
 f = open('02.txt','r',encoding='utf-8')
 移动光标到末尾
 f.seek(0,1)
 移动光标到开始
 f.seek(0)
 移动光标到当前位置
 f.seek(0,2)
 print(f.read())
 f.close()

 获取指针位置
 f = open('02.txt','r',encoding='utf-8')
 f.seek(3)
 print(f.tell())
 f.close()

 truncate  只能在可写模式下截取，对源文件截取
 f = open('02.txt','r+',encoding='utf-8')
 f.write('闪闪亮亮在家
男孩女孩')
 f.truncate(6)
 f.close()

 with open 主动关闭文件句柄在一定时间内，开启多个文件句柄
 import os
 with open('a.txt',encoding='utf-8') as f,open('a1.txt','w',encoding='utf-8') as f1:
     for line in f:
         str = line.strip().replace('alex','SB')
         f1.write(str)

 os.remove('a.txt')
 os.rename('a1.txt','a.txt')