🔀 What are If, Else and Elif in Python?
Python if, elif, and else statements allow a program to make decisions. Python evaluates a condition and executes the appropriate block of code. This is commonly used in login systems, shopping applications, banking systems, payroll software, education platforms, and many other real-world applications.
1. If, Elif and Else
if
Checks the first condition. If it is True, the associated code is executed.
Python
if age >= 18:
print("Adult")elif
Means "else if". It allows the program to test another condition.
Python
elif age >= 13:
print("Teenager")else
Executes when none of the previous conditions are True.
Python
else:
print("Child")
2. Basic If-Elif-Else Syntax
The following structure is used when a program needs
to select one result from several possible conditions.
Syntax
if condition1:
# code for condition1
elif condition2:
# code for condition2
else:
# default code
Important:
Python uses indentation to identify which statements
belong to the if, elif, or else block. Four spaces
are normally used for indentation.
3. How If-Elif-Else Works
Start Program
↓
Check if condition
↓
TRUE → Execute IF block
FALSE → Check ELIF condition
↓
TRUE → Execute ELIF block
FALSE → Execute ELSE block
4. Simple Example – Age Check
A registration system can classify a user into
different age groups.
Age Classification
age = 25
if age >= 18:
print("Adult")
elif age >= 13:
print("Teenager")
else:
print("Child")
Output:
Adult
5. Real-Time Example – Login System
A login application can check the username,
password, and account status before allowing
the user to continue.
Login Validation
username = "admin"
password = "python123"
account_active = True
if username == "admin" and password == "python123":
if account_active:
print("Login successful")
else:
print("Account is inactive")
else:
print("Invalid username or password")
Output:
Login successful
Real-world use:
Similar decision logic can be used in
employee portals, e-commerce websites,
learning systems, and administrative
applications.
6. Real-Time Example – Shopping Discount
An e-commerce website can calculate a discount
according to the customer's order amount.
E-Commerce Discount
order_amount = 7500
if order_amount >= 10000:
discount = 20
elif order_amount >= 5000:
discount = 10
elif order_amount >= 2000:
discount = 5
else:
discount = 0
discount_amount = order_amount * discount / 100
final_amount = order_amount - discount_amount
print("Discount:", discount, "%")
print("Final Amount:", final_amount)
Output:
Discount: 10 %
Final Amount: 6750.0
Business Rule:
Python checks the conditions from top to bottom.
Once one condition is True, the remaining elif
and else blocks are skipped.
7. Real-Time Example – ATM Withdrawal
An ATM can validate the withdrawal amount before
processing a transaction.
ATM Transaction
balance = 25000
withdraw_amount = 8000
if withdraw_amount <= 0:
print("Invalid withdrawal amount")
elif withdraw_amount > balance:
print("Insufficient balance")
elif withdraw_amount % 100 != 0:
print("Amount must be a multiple of 100")
else:
balance = balance - withdraw_amount
print("Withdrawal successful")
print("Remaining balance:", balance)
Output:
Withdrawal successful
Remaining balance: 17000
8. Real-Time Example – Employee Performance Bonus
A payroll system can determine the bonus percentage
based on an employee's performance rating.
Payroll Example
rating = 4.5
salary = 60000
if rating >= 4.5:
bonus_percent = 20
elif rating >= 4.0:
bonus_percent = 15
elif rating >= 3.0:
bonus_percent = 10
else:
bonus_percent = 5
bonus = salary * bonus_percent / 100
print("Bonus Percentage:", bonus_percent)
print("Bonus Amount:", bonus)
Output:
Bonus Percentage: 20
Bonus Amount: 12000.0
9. Real-Time Example – Student Grade
An education application can calculate a grade
from a student's percentage.
Grade Calculation
percentage = 82
if percentage >= 90:
grade = "A+"
elif percentage >= 80:
grade = "A"
elif percentage >= 70:
grade = "B"
elif percentage >= 60:
grade = "C"
elif percentage >= 50:
grade = "D"
else:
grade = "Fail"
print("Percentage:", percentage)
print("Grade:", grade)
Output:
Percentage: 82
Grade: A
10. Real-Time Example – Delivery Charges
An online shopping application can calculate
delivery charges according to the order total.
Delivery Charge
order_total = 850
if order_total >= 1000:
delivery_charge = 0
elif order_total >= 500:
delivery_charge = 40
else:
delivery_charge = 70
print("Delivery Charge:", delivery_charge)
Output:
Delivery Charge: 40
11. Real-Time Example – Weather Recommendation
A weather application can display different
recommendations depending on the temperature.
Weather Logic
temperature = 34
if temperature >= 40:
message = "Extreme heat - stay indoors"
elif temperature >= 30:
message = "Hot weather - stay hydrated"
elif temperature >= 20:
message = "Pleasant weather"
else:
message = "Cool weather - carry a jacket"
print(message)
Output:
Hot weather - stay hydrated
12. Nested If – Driving Eligibility
A nested if is an if statement placed inside another
if statement. It is useful when a decision depends
on multiple levels of validation.
Driving Eligibility
age = 25
has_license = True
if age >= 18:
if has_license:
print("You can drive")
else:
print("You need a driving license")
else:
print("You are not eligible to drive")
Output:
You can drive
13. Using AND / OR with If
Using AND
All conditions connected with and must be True.
AND Example
age = 25
salary = 50000
if age >= 21 and salary >= 30000:
print("Eligible for the offer")
else:
print("Not eligible")
Eligible for the offer
Using OR
At least one condition connected with or must be True.
OR Example
is_admin = False
is_manager = True
if is_admin or is_manager:
print("Access granted")
else:
print("Access denied")
Access granted
14. If vs Elif vs Else
if
Used to test the first condition. It starts the decision-making block.
if
if score >= 90:
print("Excellent")elif
Checks another condition when the previous condition was False.
elif
elif score >= 60:
print("Passed")else
Handles the default case when all previous conditions are False.
else
else:
print("Failed")
15. Common Mistakes
Missing Colon
Correct Syntax
# Incorrect
if age >= 18
print("Adult")
# Correct
if age >= 18:
print("Adult")Incorrect Indentation
Correct Indentation
# Incorrect
if age >= 18:
print("Adult")
# Correct
if age >= 18:
print("Adult")
Remember:
Python is indentation-sensitive.
Keep the statements belonging to an if, elif,
or else block consistently indented.
16. Best Practices
Keep Conditions Readable
Example
if age >= 18 and has_license:
print("Eligible")Order Conditions Carefully
Example
if score >= 90:
grade = "A"
elif score >= 75:
grade = "B"
elif score >= 60:
grade = "C"
else:
grade = "D"Use Else as the Default Case
Example
if status == "active":
print("User active")
else:
print("User unavailable")Avoid Unnecessary Nesting
Example
if age >= 18 and has_license:
print("Can drive")