File Handling in Python

File Handling in Python allows us to create, read, write, and modify files. It is widely used to store data permanently, read configuration files, generate reports, and work with logs.

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Why File Handling is Important?

• Stores data permanently
• Reads and writes large data efficiently
• Used in automation and testing frameworks
• Works with logs, reports, and test data

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Types of Files in Python

• Text Files (.txt, .csv, .log)
• Binary Files (.pdf, .jpg, .exe)

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Opening a File in Python

Python provides the open() function to work with files.

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

File Modes

Mode	Description
r	Read (default)
w	Write (overwrites file)
a	Append data
x	Create file
b	Binary mode

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Reading Files in Python

Read Entire File

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

Read Line by Line

file = open("data.txt", "r")
for line in file:
    print(line)
file.close()

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Writing to a File

file = open("data.txt", "w")
file.write("Welcome to Python File Handling")
file.close()

Note: Mode w will overwrite existing data.

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Appending Data to a File

file = open("data.txt", "a")
file.write("\nNew line added")
file.close()

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Using with Statement

The with statement automatically closes the file.

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

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Reading File Using read(), readline(), readlines()

file.read()       # Reads entire file
file.readline()   # Reads single line
file.readlines()  # Reads all lines as list

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File Handling with Exception Handling

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

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Working with Binary Files

file = open("image.jpg", "rb")
data = file.read()
file.close()

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Delete a File in Python

import os

if os.path.exists("data.txt"):
    os.remove("data.txt")
else:
    print("File does not exist")

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File Handling in Automation Testing

with open("testdata.txt", "r") as file:
    username = file.readline()
    password = file.readline()

Used in:

• Reading test data
• Writing test execution logs
• Storing API responses
• Generating reports

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Best Practices

• Always close files or use with
• Handle exceptions properly
• Use correct file mode
• Avoid hardcoding file paths

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Common Interview Questions

• What is file handling?
• Difference between read() and readline()
• What is with statement?
• Difference between w and a mode?
• How to handle file exceptions?

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Conclusion

File handling in Python is essential for data storage and automation tasks. Mastering this concept helps in building powerful Python applications and test automation frameworks.

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