Best Practices for File Handling in Python: Writing Clean, Reliable Code

The process of reading from and writing to files in a system involves interacting with file content. Python offers built-in functions and methods to handle file operations, allowing you to work with both text and binary files.

Basic File Handling Operations

Here are the basic operations involved in file handling:

1. Opening a file
2. Reading from a file
3. Writing to a file
4. Closing a file

Modes:

r –(Reaing the file, the file should be present in the system)

w- writes the data to file if it exits it overwritten. if it not there or present inside the drive then  it is created

‘a’ – Append mode:appends the data at the end without modifying the content

‘b’ – Binary mode: Opens the file in binary mode (e.g., ‘rb’, ‘wb’).

‘x’ – Exclusive creation: Creates a new file, but fails if the file already exists.

Opening a File

Syntax:

file_object = open(file_name, mode)

• file_name: The name (and path, if necessary) of the file you want to open.
• mode:whether the user is reading from or writin to.

r : ( read only)

try:

    with open(‘example.txt’, ‘r’) as file:

        content = file.read()

        print(“File Content in ‘r’ mode:”)

        print(content)

except FileNotFoundError:

    print(“File not found. Please ensure ‘example.txt’ exists.”)

2.write mode(w )

with open(‘example.txt’, ‘w’) as file:

    file.write(“text.\n”)

    print(“Data written to file .”)

 3.append mode (a)

with open(‘example.txt’, ‘a’) as file:

    file.write(“data appended.\n”)

    print(“Data appended to file .”)

4. read binary mode(rb)

try:

    with open(‘example.jpg’, ‘rb’) as file:

        binary_data = file.read()

        print(“Binary Data Read from ‘example.jpg’ .”)

except FileNotFoundError:

    print(“File not found. Please ensure ‘example.jpg’ exists.”)

5.write binary(wb)

with open(‘new_image.jpg’, ‘wb’) as file:

    file.write(b’\x89PNG\r\n\x1a\n’)

    print(“Binary data written to ‘new_image.jpg’ “)

# 6. ‘x’ (exclusive creation) mode

try:

    with open(‘new_file.txt’, ‘x’) as file:

        file.write(“This file is newly created.”)

        print(“File created successfully”)

except FileExistsError:

    print(“File already exist”)

Writing a data  to a file

—————————

# Writing to a file

with open(‘example.txt’, ‘w’) as file:

    file.write(“text\n”)

# Appending to the file

with open(‘example.txt’, ‘a’) as file:

    file.write(“This line is appended.\n”)

# Reading the file again

with open(‘example.txt’, ‘r’) as file:

    content = file.read()

    print(“Updated File Content:”)

    print(content);

Reading  a  file

———————

1. read()
2. readline()
3. readlines()

  Example 1:

The read() method reads the complete  content of the file.

With open(“hello.txt”,’r’) as file:

 content=file.read();

 print(content);

Example 2:

with open(“hello.txt”,”r”) as file:

  line=file.readline();

while line:

print(line,end=’ ‘);

line=file.readline();

Example 3:

# Open the file in read mode

with open(‘example.txt’, ‘r’) as file:

    lines = file.readlines() 

    for line in lines:

        print(line, end=”)  # Print each line without adding an extra newline

writing a file:

—————-

Top of Form

Bottom of Form

Writing to a File Example

Example1(w)

with open(‘example.txt’, ‘w’) as file:

    file.write(“This is the first line.\n”)

    file.write(“This is the second line.\n”)

    print(“Data ‘w’mode.”)

Example 2:

with open(‘example.txt’, ‘a’) as file:

    file.write(“This is an appended line.\n”)

    print(“Data ‘a’ mode.”)

Example 3:

try:

    with open(‘newfile.txt’, ‘x’) as file:

        file.write(“This file was created with ‘x’ mode.”)

        print(” created and written”)

except FileExistsError:

    print(“File already exists.”)

Explanation:

1. Write mode ‘w’:
   • In the first block, example.txt is opened in write mode (‘w’), so any existing content in the file will be overwritten.
   • file.write() is used to write each line of text into the file.
   • After this operation, example.txt will contain only the lines we wrote here, overwriting any previous content.
2. Append mode ‘a’:
   • In the second block, the file example.txt is opened in append mode (‘a’). This mode allows us to add content to the end of the file without modifying existing content.
   • We add a line of text, and it is appended at the end of the current contents of example.txt.
3. Exclusive creation mode ‘x’:
   • In the third block, newfile.txt is opened in exclusive creation mode (‘x’). This mode ensures that the file is created only if it doesn’t already exist.
   • If the file does exist, a FileExistsError is raised, and we handle it with a try-except block.