Python develops "article xxx" basic file operations----and persistent storage

##open将操作系统发起请求, the operating system completes the request,#f = open (' Old.txt ', ' r ', encoding = ' utf-8 ')#res = F.read ()#Print (res)#f.close ()#f = open (' Old.txt ', ' r ', encoding = ' utf-8 ')#res = F.readline () # #读取一行#Print (res)#f.close ()##读完文件之后必须要关闭, otherwise the file will remain in the operating system##执行以下操作可以在打开文件之后, automatically close the file#With open (' Old.txt ', ' r ', encoding = ' utf-8 ') as F:#res = F.read ()#Print (res)#Pass#f = open (' Old.txt ', ' w ', encoding = ' utf-8 ')#f.write (' 111\n ')#f.write (' 222\n ')#f.writelines ([' a\n ', ' b\n ', ' c\n ']) # #表示的是可以写入多行#f.close ()

Mode of File Open

Open mode	Execution mode
' R '	Open a file as read-only (default)
' W '	Open the file as written to overwrite the existing file
' X '	If the file already exists, using this mode throws an exception
A	Open in write mode, append at the end if the file exists
' B '	Open a file in binary mode
' t '	Open in text mode (default)
+	Readable writable mode (can be added to other modes) Universal line break support
U	Universal Line break support

Methods for File objects

Methods for File objects	Perform actions
Close ()	Close File
Read (Size=-1)	Reads a size character from a file, and reads all the remaining characters when no size or given negative value is given. Then return as a string
ReadLine ()	Reads a whole line of string from a file
Write (str)	Writes a string str to a file
Writelines (seq)	Want the file to be written to a string sequence seq,seq should be an iterative object that returns a string
Seek (Offset,from)	Move the file pointer in a file, offset from the from offset byte
Tell ()	Returns the current position in the file

There are many ways to read a file, you can use the read () and ReadLine () methods of the file object, or you can read directly from list (f) or directly using iterations. Read () reads in bytes, and if you do not set a parameter, it is all read, the file pointer points to the end of the file, and the tell () method tells you where the current pointer is.

Python develops "article xxx" basic file operations----and persistent storage