Python Nested if...else

Nested if...else allows you to write one if or else block inside another. It is used when decisions depend on multiple conditions step-by-step.

Nested if...else में एक if या else के अंदर दूसरा if या else होता है। इसका उपयोग तब होता है जब निर्णय कई शर्तों पर आधारित हो।

Why Use Nested if...else?

To check multiple related conditions in steps.
To handle complex logic with clarity.
To create real-world decision structures (like form validation, grade system, etc.).
To make your code more readable and logical.
Essential for scenarios where one decision depends on another.

Example 1: Grade Evaluation

marks = 85
if marks >= 60:
    if marks >= 90:
        print("Grade A")
    else:
        print("Grade B")
else:
    print("Fail")

Output:

Grade B

Checks if marks are above 60, then further checks for Grade A or B.

Example 2: Voting Eligibility

age = 20
id_card = 'yes'
if age >= 18:
    if id_card == 'yes':
        print("You can vote.")
    else:
        print("ID required to vote.")
else:
    print("Not eligible.")

Output:

You can vote.

Checks age and ID card before allowing to vote.

Example 3: Number Sign

num = 0
if num >= 0:
    if num == 0:
        print("Zero")
    else:
        print("Positive")
else:
    print("Negative")

Output:

Zero

Checks if a number is positive, negative, or zero.

Example 4: Login Check

username = 'admin'
password = '1234'
if username == 'admin':
    if password == '1234':
        print("Login Successful")
    else:
        print("Incorrect Password")
else:
    print("Invalid Username")

Output:

Login Successful

Checks username and then password for login.

Example 5: Check Even or Odd and Divisibility

num = 12
if num % 2 == 0:
    if num % 3 == 0:
        print("Even and divisible by 3")
    else:
        print("Even but not divisible by 3")
else:
    print("Odd number")

Output:

Even and divisible by 3

Checks if number is even and divisible by 3.