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
