Conditional Statements

On This Page

• 5.1  The if Statement
• 5.2  if-else Statement
• 5.3  Nested if
• 5.4  elif Ladder
• 5.5  match-case (Python 3.10+)
• 5.6  Logical Thinking & Flowcharts
• 5.7  Practical Exercises
• 5.8  Module Quiz (MCQs)
• 5.9  Module Assignment
• 5.10  Interview Questions — Module 5
• 5.11  Student Notes Page

Module 5: Conditional Statements

5.1  The if Statement

Conditional statements let your program make decisions — running certain code only when a condition is True. The if statement is the most basic form of decision-making.

marks = 85
if marks >= 40:
    print("Result: Pass")

5.2  if-else Statement

The else block runs when the if condition is False, giving your program two possible paths.

marks = 32
if marks >= 40:
    print("Result: Pass")
else:
    print("Result: Fail")

5.3  Nested if

A nested if is an if statement placed inside another if or else block — useful when you need to check a second condition only after the first one is satisfied.

marks = 92
if marks >= 40:
    print("Result: Pass")
    if marks >= 90:
        print("Grade: A+ (Distinction)")
    else:
        print("Grade: B")
else:
    print("Result: Fail")

5.4  elif Ladder

When you have multiple conditions to check in sequence, elif (else-if) is cleaner than multiple nested if statements.

marks = 76
if marks >= 90:
    grade = "A+"
elif marks >= 75:
    grade = "A"
elif marks >= 60:
    grade = "B"
elif marks >= 40:
    grade = "C"
else:
    grade = "Fail"
print("Grade:", grade)

5.5  match-case (Python 3.10+)

Introduced in Python 3.10, match-case is Python's version of a switch statement — useful when comparing one variable against several fixed values.

day = "MON"
match day:
    case "MON":
        print("Digital Marketing Class")
    case "WED":
        print("SEO Class")
    case "FRI":
        print("Google Ads Class")
    case _:
        print("No class scheduled")

5.6  Logical Thinking & Flowcharts

Before writing code, it helps to visualize the decision-making process as a flowchart. This builds logical thinking — a core skill for every programmer and data analyst.

Figure 5.1 — Basic if-else decision flow: the program checks a condition, then follows exactly one of two paths before continuing.

5.7  Practical Exercises

Basic (5 Questions)

1. Write a program to check if a number is positive or negative.

2. Write a program to check if a person is eligible to vote (age >= 18).

3. Check if a given number is even or odd using if-else.

4. Write a program that checks if a student passed or failed given their marks.

5. Check if a year is a leap year using basic if conditions (divisible by 4).

Intermediate (5 Questions)

1. Write a grading program using elif that assigns A+/A/B/C/Fail based on marks.

2. Check if a number is divisible by both 3 and 5 using nested if.

3. Write a program using match-case to print a message based on a day of the week.

4. Build a simple login checker that verifies both username and password using nested if.

5. Write a program to find the largest of 3 numbers using elif.

Advanced (5 Questions)

1. Build a BMI Calculator that categorizes a person as Underweight/Normal/Overweight/Obese using elif.

2. Draw a flowchart AND write the code for a simple 'course fee discount' system (student gets 10% off if fee > 10000).

3. Write a program that validates a password (must be 8+ characters AND contain at least 1 number) using nested conditions.

4. Create a simple traffic-light simulator using match-case (Red = Stop, Yellow = Get Ready, Green = Go).

5. Build a 'Loan Eligibility Checker' using nested if that checks income, age, and credit score together.

5.8  Module Quiz (MCQs)

5.9  Module Assignment

Assignment: Student Result & Grading System

• Take a student's marks (out of 100) as input.
• Use an elif ladder to assign a grade: A+ (90+), A (75-89), B (60-74), C (40-59), Fail (below 40).
• Use a nested if to add a 'Distinction' remark for any A+ grade student.
• Print a final formatted result summary using an f-string.

Expected Output: A complete grading script that correctly classifies any input marks into the right grade band and adds a distinction remark where applicable.

5.10  Interview Questions — Module 5

• Q: How does Python define code blocks without curly braces?
  A: Python uses consistent indentation (spaces or tabs) to define which lines belong to a block — incorrect indentation causes an IndentationError.
• Q: What is the difference between elif and nested if?
  A: elif checks alternative conditions when the previous ones are False, evaluating only one branch overall; nested if places an independent if inside another block, allowing multiple conditions to be checked together.
• Q: When would you use match-case instead of if-elif?
  A: match-case is cleaner when comparing a single variable against many fixed, specific values, similar to a switch statement in other languages.
• Q: Why is a flowchart useful before writing conditional logic?
  A: A flowchart visually maps out every decision path before coding, helping catch missing cases and logic errors early.

5.11  Student Notes Page

Use this space to write down key points, doubts, and your own examples from today's session.