File Handing: File handling in Python is the
way to store data in a file. These stored data can be used later for performing
various operations.
.Why we need File
Handling: Till know we are
writing programs in such a way that we are getting input from user and
returning the output. We are not storing any value/output anywhere. But in real
life applications, we make some applications which store the values and that
values can be used later for various operation.
Example: We can take the example
of login/registration system. When user do registration by filling their
information. Their info. is stored in file or databases. And later when user
logins by filling their login credentials, then it search for the details
entered by user. If details exist in file or database then user successfully
login.
How many types of
Data Files in Python?
There are three types of files in python:
1). Text files
2). Binary files
3). CSV files
(i). Text files: Text files are the files which
store information in ASCII and Unicode characters. Each line of text in text
file is terminated by EOL (End of Line) special character ie. full stop(.). We
use .txt extension for saving text files. If we do not save
our file by using .txt extension then by default extension
is file.
(ii). Binary files: Binary files stores the
information in binary format ie. 1 or 0. Our machine also uses binary languages
to store information in our memory. There is no delimiter for a line.
Translator are not require by machine to translate binary files as machine can
understand binary format text.
Translators are required in
case of text files as machine do not understand text format file. So translator
translates text to binary format and hence file is stored into the machine
memory. Binary files are more secure.
(iii) CSV files: CSV files are comma separated
values file. It is a text file.
|
Text Files |
Binary Files |
|
It stores information in ASCII and Unicode characters. |
It stores information in the form of images, audio etc. |
|
Text
files are slower as compared to binary files. |
Binary files are faster to read and write for programs. |
|
It uses
extension .txt. |
It uses
.dat extension. |
|
Special
character full stop (.) is used to terminate line. |
There
is no delimiter in Binary file. |
|
Easy to
understand by humans. |
Difficult
to understand by humans. |
File Access modes in Python
|
Mode |
Function Descriptions |
|
r |
Opens
file for reading and this is the Default Mode. |
|
rb |
Opens
file for reading only in Binary format. Default Mode for Binary files. |
|
r+ |
Opens
file for both reading and writing purposes. |
|
rb+ |
Opens
file for both reading and writing purposes in Binary format. |
|
w |
Opens file for writing only. If file already exists, then it overwrites the file else new file will be created. |
|
wb |
Opens
file for writing only in Binary format. |
|
w+ |
Opens
file for both reading and writing. |
|
wb+ |
Opens
file for both reading and writing in Binary format. |
|
a |
Opens file for appending, pointer at end of the file. If file does not exist, it
creates a new file for writing. |
|
ab |
Opens
file for appending in Binary format. |
|
a+ |
Opens
file for both appending and reading. |
|
ab+ |
Opens
file for both appending and reading in Binary format. |
Open File in Python
1). Open File: There are three types of
files ie. text file, binary files and csv files. We will talk about text file. So, to perform any
operation on input/output data and to store that data in file, we need to
create a file first in which we can store that data.
Syntax 1:
FileObject=open(‘<filename>’,
‘mode’)
Two ways are shown above to
open a file. We can use any of them. There is some difference between both
syntax. In first one, inside square bracket only one parameter
is required ie. file name/ file path.
Actually by default mode of
opening file in read mode ie ‘r’ mode. If we do not pass any mode while opening
file. Then it will open that file in read mode. In second, we
have to just pass the file mode ie. ‘r’ etc.
Syntax 2:
f =
open("test.txt") # To open a file
file.close() # To close
a file
Note: Always remember the file name or file path you are
giving should be the existing one. If file name or file path is wrong then it
will return an error!
Example 1: Example of opening of text
file.
f =
open("test.txt")
if(f):
print("File
exist")
Output
#File exist
//It must create a text
file first at the same location where your python file.
Important: This program is just for opening file. Other
operations we will perform later.
2.) Create File: Above we learned, how to open existing file. Here we will learn how to create own file if file is not already existing.
There are two ways to create a file:
1). Using open()
method
2). Using with open() statement
(i). open(): We mainly prefer to use open()
method to create a file. We will use same function ie. open() that
we have used for opening file. Only
difference is instead of opening file in read mode we will open file in write
mode.
Syntax
FileObject=open(‘<filename>’,’w’)
Here ‘w’ defines that the file
we are going to open, should be open in write mode only. We open a file in
write mode when we have to perform any operation on the data.
Example 1:
f =
open("test.txt",w)
if(f):
print("File
exist")
Here our code successfully
executed and you can see that our output and file created highlighted in
yellow.
Note: If file name given inside open function is already
exist. Then it will override the complete data in the existing file.
2). with open() statement: This is the very handy
block method. Using this method, we can perform multiple operations in a single
block. Operations we can perform like write, append, update, delete etc. The
advantage of using with open statement() is that you don’t
need to close file after performing any updation in file. Close() method is
called automatically in with open() statement.
Syntax:
With open(<FileName>,<FileMode> as
<File Handle>:
f.write(“……”)
Note: Here f.write() is the operation (write operation on
file). We will discuss about operations on file in next articles.
Example 1:
With open("abc.txt","w") as f:
f.write("Hello Students How are you")