Nested Conditional Statements with Python

Nested Conditional Statements

Introduction to Nested Conditional Statements

Nested conditional statements are used to test additional conditions within the scope of another condition. They are useful when you need to evaluate multiple criteria in a hierarchical manner. This allows for more complex decision-making processes within your code.

Syntax of Nested Conditional Statements

The basic syntax for nested conditional statements is: 

if main_condition:
    # Code to execute if the main_condition is true
    if secondary_condition:
        # Code to execute if the secondary_condition is true
    else:
        # Code to execute if the secondary_condition is false
else:
    # Code to execute if the main_condition is false

Examples of Nested Conditional Statements

Simple Example

Let’s check if a person is eligible for a program based on age and education level: 

age = 22
education = "Bachelor"
# Check eligibility for the program
if age >= 18:
    if education == "Bachelor":
        print("Eligible for the program")
    else:
        print("Not eligible due to education level")
else:
    print("Not eligible due to age")

 Explanation:

• The first if checks if age is 18 or older.
• If this condition is true, it then checks the education level.
• If both conditions are satisfied, it prints “Eligible for the program”.
• Otherwise, it prints a message indicating why the person is not eligible.

Multiple Levels of Conditions

Here’s an example of a loan approval system with multiple levels of conditions: 

age = 30
income = 50000
credit_score = 700
# Check loan eligibility
if age >= 18:
    if income >= 30000:
        if credit_score >= 650:
            print("Loan approved")
        else:
            print("Loan denied due to low credit score")
    else:
        print("Loan denied due to insufficient income")
else:
    print("Loan denied due to age")

Explanation:

• The outer if checks if age is 18 or older.
• The next level checks if income is at least 30,000.
• The innermost condition checks if credit_score is at least 650.
• The appropriate message is printed based on which conditions are met.

Best Practices for Nested Conditional Statements

• Use Reasonable Nesting Levels: Avoid excessive nesting as it can make your code harder to read and maintain. If you find yourself deeply nesting conditions, consider refactoring the code into functions or simplifying the logic.
• Clarify with Comments: Use comments to explain the logic of nested conditions, especially when the logic becomes complex. This helps others (and future you) understand the code better.
• Decompose into Functions: For complex logic, it’s often helpful to break the code into separate functions that handle different parts of the logic. This makes the code more readable and easier to test.
• Use Alternative Structures: For scenarios with many conditions, consider using alternative structures like dictionaries to map conditions to specific results, or match-case structures if you are using Python 3.10 or later.

Advanced Example

Here’s a more advanced example using nested conditions for managing club memberships: 

membership_level = "Gold"
years_of_membership = 5
attendance = 15
# Check benefits based on membership level
if membership_level == "Gold":
    if years_of_membership >= 5:
        if attendance >= 10:
            print("Gold member benefits: Premium support, Free gifts, VIP access")
        else:
            print("Gold member benefits: Premium support, Free gifts")
    else:
        print("Gold member benefits: Premium support")
elif membership_level == "Silver":
    if years_of_membership >= 3:
        print("Silver member benefits: Standard support, Discounts")
    else:
        print("Silver member benefits: Standard support")
else:
    print("Basic member benefits: Limited support")

Explanation:

• The code first checks the membership_level.
• Based on the level, it then evaluates how many years the person has been a member and their attendance.
• The benefits are printed based on the conditions met.

Debugging and Maintaining Nested Conditions

• Debugging: Use print statements or a debugger to check variable values at each level of nesting to ensure conditions are evaluated correctly.
• Maintenance: When modifying conditions, test each level of the logic to avoid introducing errors. Consider simplifying or breaking down complex conditions to make the code easier to understand and maintain.