12.4 Text File Handling in Python – A Complete Guide for Class XII CBSE

 

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🧠 What is a Text File?

A text file is a file that contains characters and lines you can read using a text editor like Notepad. Python allows you to create, read, write, and append text files using simple functions.

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🔧 File Handling Operations in Python

Python uses the built-in open() function to work with files.

✅ Basic Syntax:

python

file = open("filename.txt", "mode")
# perform file operations
file.close()

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🔍 Common File Modes:

Mode	Description
'r'	Read mode (default)
'w'	Write mode (overwrites if file exists)
'a'	Append mode
'r+'	Read and write
'w+'	Write and read (overwrites existing content)

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✍️ Writing to a Text File

python

f = open("notes.txt", "w")
f.write("Welcome to File Handling!\n")
f.write("This is a text file.")
f.close()

🔹 If the file doesn’t exist, Python creates it.
🔹 If it exists, content is overwritten in 'w' mode.

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📖 Reading from a Text File

python

f = open("notes.txt", "r")
content = f.read()
print(content)
f.close()

Other Reading Methods:

Method	Description
read(n)	Reads n characters
readline()	Reads one line at a time
readlines()	Reads all lines into a list

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➕ Appending to a Text File

python

f = open("notes.txt", "a")
f.write("\nThis line is appended.")
f.close()

✔️ No content is overwritten; new data is added at the end.

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🧭 File Pointer and seek() Method

The file pointer keeps track of the current position in the file.

python
f = open("notes.txt", "r")
f.seek(5)       # Moves pointer to the 6th character
print(f.read()) # Reads from position 5 onwards
f.close()

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⚠️ Best Practice: Use with Statement

python
with open("notes.txt", "r") as f:
    content = f.read()
    print(content)

🛡️ Advantage: Automatically closes the file, even if an error occurs.

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📌 Important Notes:

• Always close the file after operations to free resources.

• Use exception handling (try-except) to manage errors like "File Not Found".

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💡 Example Programs:

🔹 Program 1: Count the number of lines in a file

python
f = open("notes.txt", "r")
lines = f.readlines()
print("Total lines:", len(lines))
f.close()

🔹 Program 2: Search for a word in a file

python
f = open("notes.txt", "r")
word = "Python"
found = False
for line in f:
    if word in line:
        found = True
        break
f.close()
print("Word found!" if found else "Word not found.")

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❓ Practice Questions:

📘 1 Mark – Objective:

1. What does the open() function return?
2. Name the file mode used to append content.
3. Which method reads one line at a time?
4. What will readlines() return?

✍️ 2 Marks – Short Answer:

1. Differentiate between write() and writelines() with examples.
2. What happens if you try to open a non-existing file in read mode?

💻 3 Marks – Programming:

1. Write a program to display only the first 3 lines of a file.
2. Write a program to copy contents from one file to another.

🧠 5 Marks – Case-Based:

Given a file named report.txt containing student names and marks (one per line). Write a program to:

• Read the content line by line
• Display only the names of students who scored above 80

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🎯 Tips to Score Full Marks:

• Remember to close or use with to avoid losing marks.
• Use clear variable names and indentation in your code.
• Practice past year questions for better confidence.

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📝 Conclusion

Text file handling is one of the most scoring and practical topics in the CBSE Class XII syllabus. With just a few functions like open(), read(), and write(), you can perform powerful file operations that are often used in real-world applications.