File Handling in Python

File is collection of information which is stored on disk or drive. File handling is method to deal with files in system. For example, opening file, reading file, writing file, closing file, append file etc. To perform some operations with your file which is stored at your drive you can use some methods. This method is called as operations of file.

In Python we can use various functions and modules to handle files on system.

File Handling Methods in Python:

1.     Opening File:

The open () function is used to open file in Python. General syntax is as follows,

My_file=open(filename,mode)

Here filename is the name of file that you want to open and mode is nothing but the purpose for what you want to open the file.

Following are some file opening modes,

‘r’  means file will be opened for reading purpose

‘w’  means file will be opened for write purpose

‘a’  means file will be opened for append mode

‘b’ means file will be opened for binary mode

‘t’ means file will be opened for text mode

For example,

File_object=open(“Filepath”, ”r”)

 

file = open("C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt", 'r')

 

Here file is file object created to open the file. open() function is used to open a file. In open function parenthesis the location of specified file with its extension is given and then file opening mode ‘r’ is given that means file is opened for read mode.

Another example,

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt"

file=open(filepath,'r')

In above example first you can store file location in one variable and then this variable can be passed in file open () function.

 

 

2.    Reading from a file:

The read() is used to read the file contents from file. This method helps you to read entire file contents which you have opened from a specified location.  

General Syntax to open File at read Mode

with open(‘filename.txt’, ‘r’) as fileobject:

          variable=f.read()

File is opened by with method and file name is given in parenthesis to open this file for ‘r’ means read mode. This method is storing in fileobject. Then one another variable is created to store file contents. The read function is used to read the file.  

For Example,

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt"

file=open(filepath,'r')

content=file.read()

print(content)

Output:

jhegbdhfb

kjsdnkfn

alsndlknf

qlkasdlkfn

lqjasdfln

alksdnflkn

a;lsn

 

Here File path is stored into filepath variable. The file is opened by using file path and mode of opening the file is read with file object file object. Then this file is used for reading purpose with the help of read() function. If you want to display the file contents then store this process into one another variable and then by using print() function display the contents of the file.

 

The File is also opened for read mode to check the contents of file with the help of with method as follows

with open (filepath,'r') as f:

          contents=f.read()

          print(contents)

Output:

jhegbdhfb

kjsdnkfn

alsndlknf

qlkasdlkfn

lqjasdfln

alksdnflkn

a;lsn

Reading the file with readline():

The readline() function is used to read a line from file.

By default readline function will return first line only.

For example,

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt"

file=open(filepath,'r')

content=file.readline()

print(content)

Output:

Jhegbdhfb

 

To read particular line from file we can use readlines() function as follows,

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt"

file=open(filepath,'r')

content=file.readlines()

line=content[0]

line

Output:

'Hello friends h r uHello friends h r u, My name is Anthonymy name is Rohanmy name is Rohan'

 

Read File using Loop:

We can also apply loop to read file.

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt"

with open(filepath,'r') as f:

    for line in f:

        print(line)

Output:

Hello friends h r uHello friends h r u, My name is Anthonymy name is Rohanmy name is Rohan

3.    Writing To a File:

To write new contents to a file you can use write() function. To write something to a file first file should be opened.

The general syntax to open file for write mode is as follows,

File=open(“Filename.txt”, ‘w’)

Here file is file object where file opening method is stored. Open() method is used to open file. This method has two parameters one is filename is the name of file which you want to open and ‘w’ is the mode of opening the file. ‘w’ stands for write mode. When the specified file is exist it is opened and all the existing contents are replaced with new contents you write in file.

For example,

file=open("C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt",'w')

file.write("This is file handling class")

Here file is opened with write mode. Then the file object is used to write new data to file. When you add this data to your file1 then original file data will be replaced with ths new data.

If you want to see the new data is added or not in given file again you need to open same file with read mode as follows

file=open("C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt",'w')

file.write("This is file handling class")

 

file=open("C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt",'r')

content=file.read()

print(content)

Output:

'This is file handling class'

Another method to open file for write mode is as follows,

# File is opened for write mode

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file1.txt"

with open(filepath,'w') as f:

    f.write("Hello friends h r u")

 

# file is opened for read mode

with open(filepath,'r') as f:

    contents=f.read()

print (contents)

Output:

Hello friends h r u

File is opened by using with method for write mode. The by using write method the data is added to your file. And same file is then opened with read mode to check data is added or not.

Another  Example

# File is opened for write mode

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file11.txt"

with open(filepath,'w') as f:

    f.write("This is Python Class\nToday's session is File handling session\nThis is demonstration of file opening with write mode\n")

          

with open(filepath,'r') as f:

    contents=f.read()

Output:

print (contents)

This is Python Class

Today's session is File handling session

This is demonstration of file opening with write mode

 

Here file11.txt  does not exist on a specified location. When this file is opened with write mode and with the write() method new data is added then compiler has created new file11.txt on given specified location. This file is again opened at read mode and with the read() function this file data is displayed on screen.

 

4.     Append To a File:

The append() is used to add new data to existing file without overwriting or replacing the old data or existing data. When you open file with append mode then new data which you write will be added at the end of the existing file rather than replace it.

General syntax to open file at append mode is as follows,

file=open(“Filename.txt”,”a”)

file.write(“New data”)

 

Here filename.txt is the name of file which is opened at ‘a’ means append mode. Then new data is added to file with write method. Once you complete the writing new data you have to open your file with read mode and read function you can display the contents from your file.

For example,

# File opend at append mode

file=open("C:\\Users\\Admin\\Desktop\\Python Notes\\files.txt",'a')

file.write("\nHello friends how are you")

 

file=open("C:\\Users\\Admin\\Desktop\\Python Notes\\files.txt",'r')

contents=file.read()

print(contents)

Output:

Hello friends how are you

 

Another example by using with method,

#file is opened with apend mode to apend the contents in original file

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\files1.txt"

with open(filepath,'a') as f:

    f.write("Hello friends h r u, My name is Anthony\n"

    "how are you\n"

    "here is example of file handling")

# File is oepned in read mode to check contents are added in file or not

 

with open(filepath,'r') as f:

    contents=f.read()

print(contents)

Output:

Hello friends h r u, My name is Anthony

how are you

here is example of file handling

Difference Between Write () and append() in Python

In Python, the write() and append() functions are used to write content to files, but they have different behaviors:

1.    write() Function:

The write() function is used to write content to a file, starting from the beginning.
If the file already exists, using write() will overwrite its content.
If the file does not exist, a new file will be created.
It does not automatically add a newline character (\n) at the end of the written content.
It does not change the file pointer's position after writing.

2.  append() Function:

The append() function is used to append content to the end of a file.

If the file does not exist, it will be created.

If the file already exists, using append() will add content to the end of the existing content, without overwriting it.

It automatically adds a newline character (\n) at the end of the appended content.

It changes the file pointer's position to the end of the file after appending.  

Opening File in Bothe Read and Write Method with ‘r+’ or  Method

To open file for read and write both the mode you can use ‘r+’ method method. But when you want to apply read write mode on your file means you want to read and write to the file so  remember your file should be exist on you disk otherwise FileNotFoundError will occur.

Example to open file at read and write mode,

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file.txt"

with open(filepath,'r+') as f:

    contents=f.read()

    f.write("\nmy name is Rohan\n")

print(contents)

Output:

ksjhdfkg

alsndfkna

asjdlfkjl

asjdflkj

aklsdlfn

asdlkfnmy name is Rohanmy name is Rohan

my name is Rohan

The file.txt is already available on disk so it can be open for both read and write mode. ‘r+’ means file is opened for read and write mode.

 

5.     Closing The File:

When everything is done with file then your file should be closed. You can close the opened file with close() method. This method ensures that every changes you made with your file are saved to you file and your file is saved with new changes on disk.

General Syntax,

file.close()

 

For Example,

filepath = "C:\\Users\\Admin\\Desktop\\Python Notes\\file.txt"

file=open(filepath,'r')

content=file.read()

print(content)

file.close()

 

Here file.txt is opened at read mode and contents are displayed on screen. The same file is closed with close() method.

 

Renaming The File:

In Python files are removed with ‘OS’ module. The OS module can provide rename() function can be used to rename your file. The rename() method take two arguments one is old file name and second is new file name.

Following is example to use rename() method

import os

oldfile="C:\\Users\\Admin\\Desktop\\Python Notes\\file.txt"

newfile="C:\\Users\\Admin\\Desktop\\Python Notes\\renamed.txt"

os.rename(oldfile,newfile)

 

Here oldfile is a file which is available on disk with this specified location. On the same location this old file is renamed and store on disk. To rename your existing file which is present on your disk first you have to import the os module.  The with the help rename() method of os module the old file is renamed with new file.

Deleting the File:

To delete file in Python you can use os module.  From the os module remove() method is used to to remove the existing file from the disk.

For example,

import os

filepath="C:\\Users\\Admin\\Desktop\\Python Notes\\file111.txt"

os.remove(filepath)

 

To remove file from a specified location first you must import os module.

From the os module use remove() to remove the specified file. In above example file111.txt is a text file available on given location. This file is removed from disk permanently from disk with the help of remove(). You can check your file on disk. Or you can open this file at red mode to check this file is available or not.

 

filepath="C:\\Users\\Admin\\Desktop\\Python Notes\\file111.txt"

file=open(filepath,'r')

content=file.read()

print(content)

 

Error:

 FileNotFoundError: [Errno 2] No such file or directory: 'C:\\Users\\Admin\\Desktop\\Python Notes\\file111.txt'