File Handling In Python

Introduction to File Handling in Python

File handling is an essential concept in Python's programming framework. It enables you to use your Python code directly to create, read, write, and manage files. The ability to handle data storage, retrieval, and modification in a flexible manner facilitates the management and processing of huge datasets.

In this Python Tutorial, we will discuss file handling, including "What is File Handling in Python?" and when to utilize it. Additionally, file handling in Python will be covered with examples. Let's begin by talking about "What is File Handling?"

What is File Handling?

• A file is a named location used for storing data. Python has file-handling functionality, enabling users to read, write, and perform various other file-handling operations on files.
• Although the idea of file handling has been extended to many other languages, its implementation is typically difficult or time-consuming. However, this idea is simple to understand, just like other Python concepts.
• Python handles text and binary files differently, and this is significant. A text file is formed by the characters that make up each line of code.
• A unique character known as the End of Line (EOL) character, such as the comma {,} or newline character, ends each line in a file. It informs the interpreter that a new line has begun and ends the existing one.

Understanding Types of Files in Python

It's essential to understand the two main file formats in Python when working with files:

1. Text files:

• Typically ending in.txt, these files contain data in a readable format for humans to access.
• Any text editor can be used to edit the plain text that they contain.
• Text files can be handled in Python utilizing modes like a for appending, w for writing, and r for reading.

2. Binary Files:

• Unlike text files, binary files contain data like pictures, films, or computer programs that are not readable by humans. .bin or.dat are typical extensions for them.
• Similar to text files, binary files are handled by Python with the addition of a b suffix, such as rb for reading binary files and wb for writing them.

Understanding these file formats helps you select appropriate techniques for data reading and writing, ensuring effective file management in your Python programs.

Python File Operations

For this article, we will consider the following “Scholarhat.txt” file as an example.

Welcome to Python
Learn with ScholarHat
789 101

Opening a file

• Opening a file is the first step in doing any activity on it, whether writing or reading.
• The open() function in Python is used for this, and it returns a file object that lets you work with the file.
• However, we must define the mode that represents the purpose of the opening file.

f = open(filename, mode)

Wherever the mentioned mode is offered:

• r: Allows you to read an existing file. An error happens if the file is missing.
• w: Allows writing to an open file. Data in the file will be removed if it already exists. If the file doesn't exist, a new one is created.
• a: Opens a file to add data at the end. It keeps the info that already exists.
• r+: Allows you to read and write to a file. You can make changes to the file from the beginning without deleting any already-existing content.
• w+: Allows you to write and read data in a file. It erases any existing data. If the file doesn't exist, it creates a new one.
• a+: Allows you to read and append files. It adds data to the end without erasing existing content.

Working in Read mode

1. Opening the File:

file = open("Scholarhat.txt", "r")

Reading Content:

content = file.read()
print(content)

line = file.readline()
print(line)

lines = file.readlines()
print(lines)

file.close()

with open("Scholarhat.txt", "r") as file:
    content = file.read()
    print(content)

file.write("Welcome to Python\n")
file.write("Learn with ScholarHat\n")
file.write("789 101\n")

with open("Scholarhat.txt", "w") as file:
    file.write("Welcome to Python\n")
    file.write("Learn with ScholarHat\n")
    file.write("789 101\n")

file = open("Scholarhat.txt", "a")
file.write("Python is versatile.\n")
file.write("Expand your skills with ScholarHat.\n")
file.close()

file = open("Scholarhat.txt", "w")
file.write("This is a new line.\n")
file.close()  # Closes the file and saves changes

import os

def create_file(filename):
    try:
        with open(filename, 'w') as f:
            f.write('Welcome to ScholarHat!\n')
        print("File " + filename + " created successfully.")
    except IOError:
        print("Error: could not create file " + filename)

def read_file(filename):
    try:
        with open(filename, 'r') as f:
            contents = f.read()
            print(contents)
    except IOError:
        print("Error: could not read file " + filename)

def append_file(filename, text):
    try:
        with open(filename, 'a') as f:
            f.write(text)
        print("Text appended to file " + filename + " successfully.")
    except IOError:
        print("Error: could not append to file " + filename)

def rename_file(filename, new_filename):
    try:
        os.rename(filename, new_filename)
        print("File " + filename + " renamed to " + new_filename + " successfully.")
    except IOError:
        print("Error: could not rename file " + filename)

def delete_file(filename):
    try:
        os.remove(filename)
        print("File " + filename + " deleted successfully.")
    except IOError:
        print("Error: could not delete file " + filename)

if __name__ == '__main__':
    filename = "Scholarhat.txt"
    new_filename = "Scholarhat_Updated.txt"

    create_file(filename)
    read_file(filename)
    append_file(filename, "Expanding knowledge with ScholarHat.\n")
    read_file(filename)
    rename_file(filename, new_filename)
    read_file(new_filename)
    delete_file(new_filename)

File Scholarhat.txt created successfully.
Welcome to ScholarHat!

Text appended to file Scholarhat.txt successfully.
Welcome to ScholarHat!
Expanding knowledge with ScholarHat.

File Scholarhat.txt renamed to Scholarhat_Updated.txt successfully.
Welcome to ScholarHat!
Expanding knowledge with ScholarHat.

File Scholarhat_Updated.txt deleted successfully.

Example

# Step 1: Writing to a Binary File
file = open("example.bin", "wb")  # Open the file in write-binary mode
file.write(b'\xDE\xAD\xBE\xEF')   # Write some binary data to the file
file.close()  # Close the file to save changes

# Step 2: Reading from the Binary File
file = open("example.bin", "rb")  # Open the file in read-binary mode
content = file.read()             # Read the content of the file
print(content)                    # Output: b'\xde\xad\xbe\xef'
file.close()  # Close the file after reading

# Step 3: Appending to the Binary File
file = open("example.bin", "ab")  # Open the file in append-binary mode
file.write(b'\xBA\xAD\xF0\x0D')   # Append more binary data to the file
file.close()  # Close the file to save changes

# Step 4: Reading Again to Verify
file = open("example.bin", "rb")  # Open the file again in read-binary mode
content = file.read()             # Read the updated content of the file
print(content)                    # Output: b'\xde\xad\xbe\xef\xba\xad\xf0\x0d'
file.close()  # Close the file after the final read

Explanation

• Step 1: First, open the file "example.bin" in write-binary mode to create it and write binary data b'\xDE\xAD\xBE\xEF'. The changes are then saved by closing the file.
• Step 2: It involves reopening the file in read-binary mode to read and print the content, which displays the previously written data.
• Step 3: It is reopening the file in append-binary mode to include more data b'\xBA\xAD\xF0\x0D', then closing it to save the modifications.
• Step 4: Finally, in Step 4, the file is reopened in read-binary mode to ensure that the modified content includes both the original and appended data.

Handling File Exceptions in Python

Example

try:
    file = open("Scholarhat.txt", "r")  # Open the file in read mode
    read_content = file.read()          # Attempt to read the file content
    print(read_content)                # Print the file content
finally:
    file.close()  # Ensure the file is closed, even if an error occurs

Output

//Content of the file 
Welcome to Python
Learn with ScholarHat
789 101

If "Scholarhat.txt" Does Not Exist:

Error: could not read file Scholarhat.txt

Explanation