TechWith Vikas

Python File Handling – Read, Write, and Manage Files

Python provides built-in functions to create, read, write, and append files — allowing your programs to store and access data anytime.

Why File Handling?

Store user data (like login info).
Save results (logs, outputs, reports).
Work with external data (CSV, JSON, etc.)

Opening a File

file = open("example.txt", "mode")

Mode	Meaning
`'r'`	Read (default)
`'w'`	Write (overwrite)
`'a'`	Append
`'x'`	Create new file
`'b'`	Binary mode (e.g., images)
`'t'`	Text mode (default)

Reading from a File

file = open("example.txt", "r")
content = file.read()
print(content)
file.close()

Read Line-by-Line

for line in open("example.txt"):
    print(line)

Writing to a File

file = open("example.txt", "w")
file.write("Hello, world!\n")
file.write("Python File Handling is easy.")
file.close()

Note: "w" mode will overwrite the file if it already exists.

Appending to a File

file = open("example.txt", "a")
file.write("\nThis line is added at the end.")
file.close()

Best Practice: Use with Statement (Auto Closes the File)

with open("example.txt", "r") as file:
    data = file.read()
    print(data)

Useful File Methods

file.read()         # Read entire file
file.readline()     # Read one line
file.readlines()    # Read all lines (returns list)

file.write("text")  # Write string to file
file.close()        # Always close the file

Example: File Handling Workflow

filename = "notes.txt"

# Write
with open(filename, "w") as f:
    f.write("Welcome to Python File Handling!\n")

# Append
with open(filename, "a") as f:
    f.write("This line is added later.\n")

# Read
with open(filename, "r") as f:
    print(f.read())

Error Handling (Optional)

try:
    with open("file.txt", "r") as f:
        print(f.read())
except FileNotFoundError:
    print("File not found.")

Summary

Task	Method
Open file	`open("file.txt", "r")`
Read file	read( ), readline( ), readlines( )
Write file	`write( )`
Append to file	Use mode `"a"`
Safe handling	Use `with` statement