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FileMethods.md

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File Methods

File Methods

1.flush()

  • flush() method is used for flushes the internal buffer.
  • While writing the file operating system store the content of the file in the buffer and buffer content should be written into a file using 
    • flush() method 
    • when the buffer is full
  • python automatically flushes the files when closing them. but when we want to flush the data before closing them then the python built-in function .flush() is used

Syntax:

fileobj.flush()

Example:

#initialize file
fileobj=open("mydata.txt","w")

#Write content to file
fileobj.write("New Content Added")

#flush the Content buffer to file
fileobj.flush()

2.fileno()

  • fileno returns the integer file descriptor that is used by the implementation to request i/o operation
  • the file descriptor is simply indexed into a file descriptor table
  • for each process in the operating system, there is one block PCB(process control block) 
  • one of the parts of PCB keep track context of the process which is array structure called file descriptor

Syntax:

fileobj.fileno()

Example:

#initialize file
fileobj=open("mydata.txt","w")

#get file descriptor index value
index_val=fileobj.fileno()
print(index_val)

Output:

3

3.isatty()

  • isatty() return True if a file is connected with terminal device(tty)

Syntax:

fileobj.isatty()

Example:

#initialize file
fileobj=open("mydata.txt","w")

#Check whether file is connected with tty or not
val=fileobj.isatty()
print(val)

Output:

False

4.seek()

  • set the file cursor current position

Syntax:

 fileobj.seek(position)

File myfile.txt contains

Hi, I am writing simple python programm.

Example:

#initilize the file
file=open("myfile.txt","r")

#this will set file reading cursor to 6 th position
position=file.seek(6)

#read content
content=file.read()
print(content)

Output:

am writing simple python programm.

You use 0 as a position to set file reading cursor to the first position at the starting of file

5.tell()

  • this method tell the current exact file cursor position in integer

Syntax:

Fileobj.tell()

File myfile.txt contains

Hi, I am writing simple python programm.

Example:

#initilize the file
file=open("myfile.txt","r")

#read first 5 characters
data=file.read(5)

#now get the current position of file cursor
pos=file.tell()

Output:

5

Reading File methods

1.read()

  • read the bytes from the file.

2.readline()

  • read the single line from file

3.readlines()

  • read all lines in file and return list object.

Writing File methods

1.write()

  • used to write content to the file

2.writelines()

  • used to write multiple lines to the file list structure is used.