Python File Handling

What is a File?

A file is a collection of data stored on a storage device like a hard disk or SSD. In programming, files are used to save data permanently so it can be accessed later.

Python provides many functions and methods to create, read, write, and manipulate files.

Why Use Files?

To save data permanently beyond program execution.
To share data between different programs.
To store large data that does not fit into memory.
To keep logs and records.
To read configuration or input data.

Advantages of Using Files

Persistent storage of data.
Easy data sharing and backup.
Efficient management of large datasets.
Can be used for data logging and audit trails.
Supports various formats like text, CSV, JSON, binary, etc.

5 Examples of File Handling in Python

Example 1: Creating and Writing to a File

file = open('sample.txt', 'w')
file.write('Hello, this is a sample file.')
file.close()

Output:
Creates 'sample.txt' and writes text into it.

This code opens a file named 'sample.txt' in write mode and writes a string, then closes the file.

Example 2: Reading a File

file = open('sample.txt', 'r')
content = file.read()
print(content)
file.close()

Output:
Hello, this is a sample file.

This code reads the entire content of 'sample.txt' and prints it.

Example 3: Appending to a File

file = open('sample.txt', 'a')
file.write('\nThis line is appended.')
file.close()

Output:
Appends a new line to the existing file.

This code opens 'sample.txt' in append mode and adds a new line to the file.

Example 4: Using with Statement for File Handling

with open('sample.txt', 'r') as file:
    content = file.read()
    print(content)

Output:
Hello, this is a sample file.
This line is appended.

Using 'with' automatically closes the file after block execution.

Example 5: Reading File Line by Line

with open('sample.txt', 'r') as file:
    for line in file:
        print(line.strip())

Output:
Hello, this is a sample file.
This line is appended.

Reads file line by line and prints each line after removing trailing spaces.