Exception Handling in Python

Python Made Easy - (Article 13) Telugu Explanation

3 min readNov 1, 2025

1. Introduction - What is an Exception?

Suppose nenu program lo divide chesthunnanu

a = 10
b = 0
print(a / b)

Output:

ZeroDivisionError: division by zero

Program crash ayipoyindi!
Ila unexpected errors ni Exceptions antaru.

So, Exception Handling ante - “error vasthe program crash kakunda handle cheyyadam”.

2. Why We Need Exception Handling?

Without exception handling,
program stop aipothundi → next code execute avadhu.

With exception handling,
manam “error vache chance unna code” ni try chestham,
and “error vaste” manam neat ga handle chestham.

3. Basic Syntax of try - except

try:
    # risky code
except:
    # handle error

Example:

try:
    a = 10 / 0
except:
    print("Something went wrong!")

Output:

Something went wrong!

Explanation:

try block lo error vache code untundi.
except block error vasthe execute avuthundi.
So program crash avvakunda safe ga run avutundi.

4. Handling Specific Exceptions

Manam specific error type ni handle cheyyachu

try:
    num = int(input("Enter a number: "))
    print(10 / num)
except ZeroDivisionError:
    print("Cannot divide by zero!")
except ValueError:
    print("Please enter a valid number!")

Output examples:

If user gives 0 → Cannot divide by zero!
If user gives "abc" → Please enter a valid number!

Advantage:
Different errors ni different ways lo handle cheyyachu.

5. Using `else` Block

else block eppudu execute avuthundi ante, only if try block lo error raledu annapudu.

try:
    num = int(input("Enter a number: "))
    print(10 / num)
except ZeroDivisionError:
    print("Cannot divide by zero!")
else:
    print("Division successful!")

Output:

Enter a number: 5
Division successful!

Explanation:

Error raledu → else block execute ayindi.

6. Using `finally` Block

finally block always execute avuthundi — error vasthe kuda, raani kuda.

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Example:

try:
    file = open("data.txt", "r")
    print(file.read())
except FileNotFoundError:
    print("File not found!")
finally:
    print("Closing file...")

Output:

File not found!
Closing file...

Explanation:
finally block lo usually cleanup actions (like closing file, disconnecting DB) chestam.

7. Nested try - except Example

try:
    a = int(input("Enter number: "))
    try:
        print(10 / a)
    except ZeroDivisionError:
        print("Cannot divide by zero!")
except ValueError:
    print("Please enter a valid integer!")

Explanation:

First inner block division try chesthundi
Outer block input type check chesthundi

8. Raising Custom Exceptions

Sometimes manam custom error message create cheyyali ante raise keyword vaadali.

Example:

age = int(input("Enter your age: "))

if age < 18:
    raise Exception("You must be 18 or older!")
else:
    print("Welcome!")

Output (if age 15):

Exception: You must be 18 or older!

9. Creating Your Own Exception Class

Custom class create cheyyadam advanced but easy

class InvalidAgeError(Exception):
    pass

try:
    age = int(input("Enter your age: "))
    if age < 18:
        raise InvalidAgeError
    else:
        print("Valid age!")
except InvalidAgeError:
    print("Age must be 18 or above!")

10. Key Takeaways

Main idea:
Exception handling → program safe & professional ga nadustundi, crash kakunda!

11. Practice Questions

1️.Divide two numbers input ga tiskoni handle all errors (ZeroDivisionError, ValueError).
2️.Try to open a file that doesn’t exist — handle error neatly.
3️.Create a custom exception for “invalid password”.
4️.Use finally block to print “Program Completed” every time.