File Attributes and Stream In File Handling (Python)

FILE I/O ATTRIBUTES

Various attributes are related to file when it is opened or closed.

Those attributes are explained in the table:

Attribute	Description
name	Returns the name of the file (Including path)
mode	Returns mode of the file. (r or w etc.)
encoding	Returns the encoding format of the file
closed	Returns True if the file closed else returns False

For Example:

f = open("D:\\story.txt", "r")

print("Name of the File: ", f.name)

print("\n File-Mode : ", f.mode)

print("File encoding format : ", f.encoding)

print("Is File closed? ", f.closed)

f.close()

print("Is File closed? ", f.closed)

OUTPUT:

Name of the File: D:\story.txt

File-Mode : r

File encoding format : cp1252

Is File closed? False

Is File closed? True

Relative and Absolute Paths :

We all know that the files are kept in directory which are also known as folders.

 Every running program has a current directory. Which is generally a default directory and python always see the default directory first.

The absolute paths are from the topmost level of the directory structure. The relative paths are relative to the current working directory denoted as a dot(.) while its parent directory is denoted with two dots(..).

OS module provides many such functions which can be used to work with files and directories. OS means Operating System.

Function used to find the current directory

getcwd( ) is a function which can be used to identify the current working directory.

For this : You have to import os module

For example,

>>> import os         # importing os module

>>> cwd=os.getcwd()       # getcwd function will return the path and store in cwd variable

>>> print(cwd)       # printing current path

OUTPUT

C:\Users\dell\AppData\Local\Programs\Python\Python37-32

STANDARD FILE STREAMS :

Standard file streams are realted to standard input and output device. Keyboard is a standard input device. Monitor/screen is a standard ouput device. Similarly, any error occurs is also displayed on a screen. So the monitor is also standard error device. That is,

Standard input device(stdin)    -           reads from keyboard

Standard output device(stdout)          -           prints on screen

Standard error device(stderr)  -           prints error on screen

In python. These devices are implemented as files known as standard streams.

To read data from the keyboard and to write data on a screen, we have to import module sys such as:

import sys

for reading, use function: sys.stdin.read()

for writing, use function: sys.stdout.write()

for writing error, use function : sys.stderr.write()

For example,

Reading and writing using stdin and stdout

import sys

f=open("book1.txt","r+")

ch=sys.stdin.read(3)         #whatever is read from the keyboard, return 3                         

                                              # characters from keyboard file and store in variable ch

print(ch)

sys.stdout.write(ch)

sys.stdin.read(5)

sys.stderr.write("\nNo errors occured\n")

import sys

f=open("book1.txt")

line1=f.readline()

line2=f.readline()

line3=f.readline()

sys.stdout.write(line1)

sys.stdout.write(line2)

sys.stdout.write(line3)

sys.stderr.write("\nNo errors occured\n")

f.close()

OUTPUT

welcome to python.          # written by keyboard

wel                                         # read 3 characters from stdin

No errors occurred                        # printing message

delhi is a capital of India.

delhi is a vast city

delhi has more than 1 crore population

No errors occured