Python File Handling

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Python File Handling

File handling plays a crucial role in many applications, especially when working with data storage, logs, uploads, or configuration files.

Python provides built-in functions that allow you to create, read, modify, and remove files easily, without needing extra libraries.

Working with Files in Python

The primary function used for file operations in Python is open().

This function connects your program to a file and returns a file object that you can work with.

Basic Syntax

# Syntax demonstration (not runnable) file_object = open("filename.txt", "mode")

# Syntax guide - requires valid file to execute

• filename → Name (or path) of the file
• mode → Specifies how the file should be opened

File Open Modes

Python provides several modes for opening a file:

Mode	Description
"r"	Read - Default value. Opens a file for reading, error if the file does not exist
"a"	Append - Opens a file for appending, creates the file if it does not exist
"w"	Write - Opens a file for writing, creates the file if it does not exist
"x"	Create - Creates the specified file, returns an error if the file exists
"t"	Text - Default value. Text mode
"b"	Binary - Binary mode (e.g. images)

Example: Binary Modes

# Simulating opening binary files try: file = open("image.jpg", "rb") print("Opened image.jpg for reading in binary.") file.close() except FileNotFoundError: print("Error: image.jpg not found.") file2 = open("output.jpg", "wb") print("Opened output.jpg for writing in binary.") file2.close()

Error: image.jpg not found. Opened output.jpg for writing in binary.

Opening a File for Reading

Example: Default Read Mode

try: data = open("notes.txt") print("File opened successfully.") data.close() except FileNotFoundError: print("File not found.")

File not found.

This works because the default mode is "rt" (Read Text).

Equivalent Code

try: data = open("notes.txt", "rt") print("File opened successfully.") data.close() except FileNotFoundError: print("File not found.")

File not found.

Example: Reading File Content

# First, let's create the file so we can read it with open("notes.txt", "w") as f: f.write("Hello! Welcome to Python file handling.") # Now, let's read the file file = open("notes.txt", "r") content = file.read() print(content) file.close()

Hello! Welcome to Python file handling.

Note: Always remember to close the file after finishing operations.

Example: Using with Statement

# Ensure the file exists with open("notes.txt", "w") as f: f.write("This file will close automatically!") # Read using the 'with' statement with open("notes.txt", "r") as file: print(file.read())

This file will close automatically!

Note: This approach is cleaner and safer, as it automatically closes the file even if an error occurs.

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