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“A program that forgets everything when it closes isn't very useful. File handling teaches Python how to remember!”
🌟 Welcome to File Handling!
Imagine you create a Python program that stores student marks.
You run the program:
Raman - 92
Aman - 85
Priya - 96
Everything works perfectly.
But then you close Python.
The next time you run the program...
Everything is gone! 😱
Why?
Because the data was stored only in the computer's memory.
To permanently store information, we can use files.
Python Program
↓
Data
↓
File
↓
Saved permanently
This is called File Handling.
1. What is File Handling?
File handling means using Python to:
Create files
Open files
Read files
Write files
Add new information
Modify stored information
Work with structured data
Handle file-related errors
For example, Python can work with:
students.txt
marks.csv
students.json
2. Why Do We Need Files?
Consider a school management program.
It might need to store:
Student Name
Roll Number
Class
Marks
Address
Phone Number
If we store this information only in variables:
name = "Raman"
marks = 92
the information exists only while the program is running.
When the program stops, the variables disappear.
But if we save the information in a file:
students.txt
we can retrieve it later.
🧠 Python Pebble
Variables remember data temporarily. Files allow us to store data for future use.
3. Opening a File
Python provides the open() function.
Basic syntax:
file = open("filename.txt", "mode")
For example:
file = open("students.txt", "r")
Here:
students.txt → file name
r → read mode
4. File Modes
The mode tells Python what we want to do with the file.
| Mode | Meaning |
|---|---|
r | Read |
w | Write |
a | Append |
x | Create a new file |
r+ | Read and write |
w+ | Write and read |
a+ | Append and read |
The most important modes for beginners are:
r → Read
w → Write
a → Append
5. Reading a File 📖
Suppose students.txt contains:
Raman
Aman
Priya
We can read it using:
file = open("students.txt", "r")
data = file.read()
print(data)
file.close()
Output:
Raman
Aman
Priya
6. Why Do We Need close()?
When Python opens a file, it uses a system resource.
After finishing our work, we should close it.
file.close()
So the traditional pattern is:
file = open("students.txt", "r")
data = file.read()
print(data)
file.close()
But there is an even better way.
7. The Better Way – with open() ⭐
Python provides a safer and cleaner approach:
with open("students.txt", "r") as file:
data = file.read()
print(data)
Python automatically closes the file after the with block.
This means we don't need:
file.close()
🧠 Python Pebble
Prefer
with open()when working with files.
It makes programs:
Safer
Cleaner
Easier to understand
8. Reading Line by Line
Instead of reading the entire file at once, we can process each line.
with open("students.txt", "r") as file:
for line in file:
print(line)
If the file contains:
Raman
Aman
Priya
Python processes:
Raman
Aman
Priya
one line at a time.
This is particularly useful for large files.
9. readline()
We can read one line at a time using readline().
with open("students.txt", "r") as file:
print(file.readline())
print(file.readline())
If the file contains:
Raman
Aman
Priya
Output:
Raman
Aman
10. readlines()
readlines() reads all lines and returns them as a list.
with open("students.txt", "r") as file:
lines = file.readlines()
print(lines)
Output:
['Raman\n', 'Aman\n', 'Priya\n']
Notice the \n.
It represents a new line.
11. Removing the New Line
We can use strip().
with open("students.txt", "r") as file:
for line in file:
print(line.strip())
Output:
Raman
Aman
Priya
12. Writing to a File ✍️
Now let's create a file.
with open("students.txt", "w") as file:
file.write("Raman\n")
file.write("Aman\n")
file.write("Priya\n")
The file will contain:
Raman
Aman
Priya
13. Important: Write Mode Can Replace Existing Data ⚠️
Suppose the file already contains:
Raman
Aman
Priya
Now we run:
with open("students.txt", "w") as file:
file.write("Rahul\n")
The previous contents are replaced.
The file now contains:
Rahul
🧠 Remember
wmeans write/overwrite.
Be careful!
14. Appending Data ➕
What if we want to add information without deleting existing data?
Use a.
with open("students.txt", "a") as file:
file.write("Neha\n")
If the file originally contains:
Raman
Aman
Priya
after appending:
Raman
Aman
Priya
Neha
🧠 Python Pebble
w→ Replacea→ Add to the end
15. Writing Multiple Lines
We can use writelines().
students = ["Raman\n", "Aman\n", "Priya\n"]
with open("students.txt", "w") as file:
file.writelines(students)
The file becomes:
Raman
Aman
Priya
16. Text Files
A normal .txt file is a text file.
Example:
student.txt
It can contain:
Name: Raman
Class: 9
Marks: 92
Python can read this information as text.
with open("student.txt", "r") as file:
data = file.read()
print(data)
17. Creating a Simple Notes Program 📝
Let's build something useful.
note = input("Enter your note: ")
with open("notes.txt", "a") as file:
file.write(note + "\n")
print("Note saved successfully!")
Example:
Enter your note: Complete Python homework
Note saved successfully!
Every time the program runs, a new note is added.
18. Reading Our Notes
with open("notes.txt", "r") as file:
notes = file.read()
print("My Notes")
print("--------")
print(notes)
We have now created a tiny digital notebook using Python!
19. Handling File Errors 🚨
What happens if we try to open a file that doesn't exist?
with open("unknown.txt", "r") as file:
print(file.read())
Python may generate:
FileNotFoundError
Instead of allowing the program to crash, we can handle the error.
20. Using try-except
try:
with open("unknown.txt", "r") as file:
print(file.read())
except FileNotFoundError:
print("File does not exist.")
Output:
File does not exist.
Now our program is much more user-friendly.
21. Other Common File Exceptions
Some useful exceptions include:
| Exception | Meaning |
|---|---|
FileNotFoundError | File doesn't exist |
PermissionError | File cannot be accessed |
IsADirectoryError | A directory was used where a file was expected |
UnicodeDecodeError | File encoding could not be decoded |
For beginners, the most important one is:
FileNotFoundError
22. Reading and Writing Structured Data
So far, we stored simple text.
But real applications often store structured information.
For example:
Roll No: 101
Name: Raman
Marks: 92
Or:
101,Raman,92
102,Aman,85
103,Priya,96
Or:
{
"roll": 101,
"name": "Raman",
"marks": 92
}
Python supports several ways to work with structured data.
Two important formats are:
CSV
JSON
23. CSV Files 📊
CSV stands for:
Comma-Separated Values
A CSV file might look like this:
Roll,Name,Marks
101,Raman,92
102,Aman,85
103,Priya,96
CSV is commonly used for:
Student records
Employee data
Sales data
Marks
Expenses
Reports
24. Writing a CSV File
Python has a built-in csv module.
import csv
students = [
[101, "Raman", 92],
[102, "Aman", 85],
[103, "Priya", 96]
]
with open("students.csv", "w", newline="") as file:
writer = csv.writer(file)
writer.writerow(["Roll", "Name", "Marks"])
writer.writerows(students)
This creates:
Roll,Name,Marks
101,Raman,92
102,Aman,85
103,Priya,96
25. Reading a CSV File
import csv
with open("students.csv", "r") as file:
reader = csv.reader(file)
for row in reader:
print(row)
Output:
['Roll', 'Name', 'Marks']
['101', 'Raman', '92']
['102', 'Aman', '85']
['103', 'Priya', '96']
Notice that values read from CSV are generally strings.
If we need marks as numbers:
marks = int(row[2])
26. CSV Using Dictionaries
A very useful approach is DictReader.
import csv
with open("students.csv", "r") as file:
reader = csv.DictReader(file)
for row in reader:
print(row["Name"], row["Marks"])
Output:
Raman 92
Aman 85
Priya 96
This is easier to understand because we can use column names.
27. JSON Files 🤖
JSON stands for:
JavaScript Object Notation
Don't let the name worry you!
JSON is simply a popular format for storing structured data.
Example:
{
"name": "Raman",
"class": 9,
"marks": 92
}
JSON is commonly used by:
Websites
Apps
APIs
Databases
AI applications
Data exchange systems
28. Writing JSON Using Python
Python provides the json module.
import json
student = {
"roll": 101,
"name": "Raman",
"class": 9,
"marks": 92
}
with open("student.json", "w") as file:
json.dump(student, file, indent=4)
The file contains:
{
"roll": 101,
"name": "Raman",
"class": 9,
"marks": 92
}
29. Reading JSON
import json
with open("student.json", "r") as file:
student = json.load(file)
print(student)
Output:
{'roll': 101, 'name': 'Raman', 'class': 9, 'marks': 92}
We can access individual values:
print(student["name"])
print(student["marks"])
Output:
Raman
92
30. JSON with Multiple Students
We can store a list of dictionaries.
import json
students = [
{
"roll": 101,
"name": "Raman",
"marks": 92
},
{
"roll": 102,
"name": "Aman",
"marks": 85
},
{
"roll": 103,
"name": "Priya",
"marks": 96
}
]
with open("students.json", "w") as file:
json.dump(students, file, indent=4)
Now we have a structured student database stored in a file!
31. Reading Structured JSON Data
import json
with open("students.json", "r") as file:
students = json.load(file)
for student in students:
print(
student["roll"],
student["name"],
student["marks"]
)
Output:
101 Raman 92
102 Aman 85
103 Priya 96
32. Updating JSON Data
Suppose Raman's marks change from 92 to 95.
We can:
Read the file
Modify the data
Write it back
import json
with open("students.json", "r") as file:
students = json.load(file)
for student in students:
if student["roll"] == 101:
student["marks"] = 95
with open("students.json", "w") as file:
json.dump(students, file, indent=4)
This is the basic idea behind many real-world data-management programs.
33. Text vs CSV vs JSON
Which format should we use?
| Format | Best For |
|---|---|
| TXT | Simple text |
| CSV | Tables and spreadsheet-like data |
| JSON | Structured/nested data |
For example:
TXT
Raman
Aman
Priya
CSV
101,Raman,92
102,Aman,85
JSON
{
"roll": 101,
"name": "Raman",
"marks": 92
}
34. File Handling + String Processing
Remember our previous Python Pebble about strings?
File handling and strings work very well together.
Suppose a file contains:
Python is easy
Python is powerful
Python is fun
We can count the number of times Python appears.
with open("message.txt", "r") as file:
data = file.read()
count = data.lower().count("python")
print("Python appears", count, "times.")
Output:
Python appears 3 times.
Now we are combining:
Files + Strings + Conditions + Counting
That's how programming becomes powerful!
35. Mini Project – Student Record Management 🎓
Let's build something bigger.
Our application will store student information in a JSON file.
Each student will have:
Roll Number
Name
Class
Marks
We will create a menu:
===== STUDENT RECORD MANAGEMENT =====
1. Add Student
2. View Students
3. Search Student
4. Update Marks
5. Delete Student
6. Exit
36. Step 1 – Load Existing Records
import json
FILE_NAME = "students.json"
def load_students():
try:
with open(FILE_NAME, "r") as file:
return json.load(file)
except FileNotFoundError:
return []
If the file doesn't exist, we return an empty list.
37. Step 2 – Save Records
def save_students(students):
with open(FILE_NAME, "w") as file:
json.dump(students, file, indent=4)
This function stores the current records.
38. Step 3 – Add a Student
def add_student(students):
roll = input("Enter roll number: ")
name = input("Enter student name: ")
student_class = input("Enter class: ")
marks = float(input("Enter marks: "))
student = {
"roll": roll,
"name": name,
"class": student_class,
"marks": marks
}
students.append(student)
save_students(students)
print("Student added successfully!")
39. Step 4 – Display Students
def view_students(students):
if not students:
print("No student records found.")
return
for student in students:
print(
f"Roll: {student['roll']}, "
f"Name: {student['name']}, "
f"Class: {student['class']}, "
f"Marks: {student['marks']}"
)
40. Step 5 – Search Student
def search_student(students):
roll = input("Enter roll number to search: ")
for student in students:
if student["roll"] == roll:
print("\nStudent Found")
print("Name:", student["name"])
print("Class:", student["class"])
print("Marks:", student["marks"])
return
print("Student not found.")
41. Step 6 – Update Marks
def update_marks(students):
roll = input("Enter roll number: ")
for student in students:
if student["roll"] == roll:
new_marks = float(
input("Enter new marks: ")
)
student["marks"] = new_marks
save_students(students)
print("Marks updated successfully!")
return
print("Student not found.")
42. Step 7 – Delete a Student
def delete_student(students):
roll = input("Enter roll number: ")
for student in students:
if student["roll"] == roll:
students.remove(student)
save_students(students)
print("Student deleted successfully!")
return
print("Student not found.")
43. Step 8 – Create the Menu
Now let's bring everything together.
def main():
students = load_students()
while True:
print("\n===== STUDENT RECORD MANAGEMENT =====")
print("1. Add Student")
print("2. View Students")
print("3. Search Student")
print("4. Update Marks")
print("5. Delete Student")
print("6. Exit")
choice = input("Enter your choice: ")
if choice == "1":
add_student(students)
elif choice == "2":
view_students(students)
elif choice == "3":
search_student(students)
elif choice == "4":
update_marks(students)
elif choice == "5":
delete_student(students)
elif choice == "6":
print("Thank you!")
break
else:
print("Invalid choice.")
Finally:
main()
44. Complete Student Record Program
import json
FILE_NAME = "students.json"
def load_students():
try:
with open(FILE_NAME, "r") as file:
return json.load(file)
except FileNotFoundError:
return []
def save_students(students):
with open(FILE_NAME, "w") as file:
json.dump(students, file, indent=4)
def add_student(students):
roll = input("Enter roll number: ")
name = input("Enter student name: ")
student_class = input("Enter class: ")
marks = float(input("Enter marks: "))
student = {
"roll": roll,
"name": name,
"class": student_class,
"marks": marks
}
students.append(student)
save_students(students)
print("Student added successfully!")
def view_students(students):
if not students:
print("No student records found.")
return
for student in students:
print(
f"Roll: {student['roll']}, "
f"Name: {student['name']}, "
f"Class: {student['class']}, "
f"Marks: {student['marks']}"
)
def search_student(students):
roll = input("Enter roll number to search: ")
for student in students:
if student["roll"] == roll:
print("\nStudent Found")
print("Name:", student["name"])
print("Class:", student["class"])
print("Marks:", student["marks"])
return
print("Student not found.")
def update_marks(students):
roll = input("Enter roll number: ")
for student in students:
if student["roll"] == roll:
new_marks = float(input("Enter new marks: "))
student["marks"] = new_marks
save_students(students)
print("Marks updated successfully!")
return
print("Student not found.")
def delete_student(students):
roll = input("Enter roll number: ")
for student in students:
if student["roll"] == roll:
students.remove(student)
save_students(students)
print("Student deleted successfully!")
return
print("Student not found.")
def main():
students = load_students()
while True:
print("\n===== STUDENT RECORD MANAGEMENT =====")
print("1. Add Student")
print("2. View Students")
print("3. Search Student")
print("4. Update Marks")
print("5. Delete Student")
print("6. Exit")
choice = input("Enter your choice: ")
if choice == "1":
add_student(students)
elif choice == "2":
view_students(students)
elif choice == "3":
search_student(students)
elif choice == "4":
update_marks(students)
elif choice == "5":
delete_student(students)
elif choice == "6":
print("Thank you!")
break
else:
print("Invalid choice.")
main()
🧪 Sample Run
===== STUDENT RECORD MANAGEMENT =====
1. Add Student
2. View Students
3. Search Student
4. Update Marks
5. Delete Student
6. Exit
Enter your choice: 1
Enter roll number: 101
Enter student name: Raman
Enter class: 9
Enter marks: 92
Student added successfully!
Now the information is stored in:
students.json
Even if the program is closed, the record remains.
That is the real power of file handling!
🧠 Python Pebble Challenge 1 – Predict the Output
Suppose data.txt contains:
Python
Programming
What will this program display?
with open("data.txt", "r") as file:
data = file.read()
print(len(data))
Don't run it immediately.
Count the characters yourself!
🧠 Python Pebble Challenge 2 – Find the Bug
What's wrong here?
file = open("students.txt", "r")
data = file.read()
print(data)
Hint
Think about resource management.
How could with open() improve this code?
🧠 Python Pebble Challenge 3 – Append Data
Write a program that:
Asks the user for their name.
Adds the name to
names.txt.Does not delete previous names.
🧠 Python Pebble Challenge 4 – Count Words
Create a program that reads story.txt and displays:
Number of words: 125
Hint
Use:
split()
🧠 Python Pebble Challenge 5 – Find a Student
Create a program that reads students.json and searches for a student using their roll number.
Display:
Student Found
Name: Raman
Marks: 92
or:
Student not found.
🏆 Master Challenge – Improve the Student Management System
The basic project is only the beginning.
Try adding:
Level 1
Calculate average marks
Find highest marks
Find lowest marks
Count students
Level 2
Search by name
Search by class
Sort students by marks
Display students scoring above 90
Level 3
Calculate grades
Prevent duplicate roll numbers
Validate marks between 0 and 100
Handle invalid numeric input
Add date of birth
Level 4 🚀
Add:
Attendance
Subject-wise marks
Percentage
Grade
Rank
Export to CSV
Import from CSV
JSON backup
Student report generation
Now you've moved from a simple Python program to a small Student Management Application.
📌 File Handling Quick Revision
| Concept | Python |
|---|---|
| Open file | open() |
| Read entire file | read() |
| Read one line | readline() |
| Read all lines | readlines() |
| Write | write() |
| Write multiple lines | writelines() |
| Automatically close | with open() |
| Read mode | r |
| Write mode | w |
| Append mode | a |
| Create new file | x |
| CSV | csv module |
| JSON | json module |
| Handle missing file | FileNotFoundError |
🎯 TXT vs CSV vs JSON – Remember This
Think of three different notebooks.
📒 TXT
Good for simple notes.
Python is fun.
Python is powerful.
📊 CSV
Good for tables.
Roll,Name,Marks
101,Raman,92
102,Aman,85
🗂️ JSON
Good for structured information.
{
"roll": 101,
"name": "Raman",
"marks": 92
}
🪨 One Final Python Pebble
File handling connects many Python concepts together:
FILE HANDLING
│
┌──────────┼──────────┐
↓ ↓ ↓
TXT CSV JSON
│ │ │
└──────────┼──────────┘
↓
Python Data
↓
┌─────────┼─────────┐
↓ ↓ ↓
Read Write Update
│ │ │
└─────────┼─────────┘
↓
REAL PROJECTS
↓
Student Record System
The important thing to remember is:
A good program processes data. A useful program also knows how to save that data.
Once you understand file handling, your Python programs don't have to forget everything when they close.
You can now build programs that store, retrieve, search, update and manage real information.
🚀 Your Next Mission
Build these projects in order:
📝 Digital Notes App
📖 Simple Diary
📊 Marks Record using CSV
🗂️ Contact Book using JSON
🎓 Student Record Management System
And then challenge yourself:
Can you build a complete Student Management System that stores all its data in JSON and also generates a CSV report?
That's your next Python Pebble!
