Quick Introduction to Python File Handling

In This Article You Will Learn About Python File Handling

Python File Handling – Before moving ahead, let’s know a little bit about Python String format () Types

Generally, a file containing lots of coding lines and helps a language perform an action is a file.

Python File – Opening File is an important feature of Python. In Python, a file allows so many features like opening, reading, writing, editing, deleting, etc. 

Python has a built-in function for working with files i.e., open () function.

open () function – Python works with files such as opening, reading, and writing, etc.

Syntax – open (filename, mode)
Parameter Values –

filename – A file that is needed to work with.

There are four different values of mode for opening a file -

‘r’ – Read – It is the default value. Opens a file for reading, if the file does not exist, return an error.

‘a’ – Append – It adds content to the existing file. Create a file, if the file does not exist.

‘w’ – Write – It writes the lines in the file. Create a file, if the file does not exist.

‘x’ – Create – It creates a file. Returns an error if the file already exists.

Apart from the above all, there are two additional ways to handle files in binary or text mode.  

‘t’ – Text – It is the default value. Open a file in text mode.

‘b’ – Binary – It opens a file in binary mode. For example – images.

Let’s get started with Python key function –

Example – Using an open () function to open a file with the file name.

File = open (myfirstfile.py)
print (File)

Note: If a file does not exist, it returns an error.

Example – Using an open () function to open a file with a file address.

File = open (write file address.py)
print (File)

Note: If a file does not exist, it returns an error.

Example – Using mode ‘r’, to read a file.

File = open (myfirstfile.py, ‘r’)
print(File.read())

Note: If a file does not exist, it returns an error.

Read Only a few lines of the file –

By default, mode ‘r’ returns whole text or content written in the file but by specifying number you can decide how much content to read.

Example – Using mode ‘r’ with a number to specify how much content to read

File = open (myfirstfile.py, ‘r’)
print(File.read(21))
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Read Lines – By using method readline(), you can return the file’s content line by line.     

Example – Using mode ‘r’, to read a file.

File = open (myfirstfile.py, ‘r’)
print(File.readline())
python-file-handling

Similarly, as many as you call the readline() method, you will get that many lines.

Example – Using mode ‘r’, to read a file.

File = open (myfirstfile.py, ‘r’)

print(File.readline())
print(File.readline())
print(File.readline())
python-file-handling

For Loop – By using for loop, you can get all lines of file one by one.

File = open (myfirstfile.py, ‘r’)

for z in File:
    print(z)
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Here’s data stored in a file – myfirstfile.py

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Close File – By using the method close(), you can close a file.

Example – Closing a file after reading it.

File = open (myfirstfile.py, ‘r’)

print(File.readline())

File.close()

Note: Changes may not show in the file until you close it or open it again.

Writing an existing file – To write in an existing file, first open a file by using the open () function and append or add content by using mode ‘a’.

‘a’ – It will append lines at the end of the file in the existing file.

‘w’ – It will write the lines in the file.

Example – Adding a new line to file – myfirstfile.py.

File = open (myfirstfile.py, ‘a’)

File.write(‘This new line is added.’)

File.close()

print(File)

Before adding a line – showing existing data of file

python-file-handling

After adding line

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Now read the file after adding lines.

File = open('myfirstfile.py', 'r')

print(File.read())
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Open a new file and overwrite the line.

File = open(newfile.py, ’w’)

File.write(‘This line is added after deleting previous lines.’)

File.close()
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Now read the file after adding lines –

File = open (myfirstfile.py, ‘r’)

print(File.read())

Note: ‘w’ method will change the whole content inside of a file.

Delete a file – By importing the Python OS module, we can delete a file.

remove() – It is a method that helps to delete a file.

import os
os.remove(‘myfirstfile.py’)
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Check if the file still exists –

By using the if… else condition, you can save to get an error, if the file is already deleted.

Example – Checking whether the file is still existing or is already deleted.

import os

if os.path.exists("myfirstfile.py"):
  os.remove("myfirstfile.py")
else:
  print("The file is no longer.")

Delete Folder – By using os.rmdir() method, you can delete an entire folder.

Example – Deleting the whole folder.

import os
os.rmdir("pythonfilefolder")

Note: You can only remove empty folders.

If you find anything incorrect in the above-discussed topic and have any further questions, please comment below.

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