Python Operators & Conditionals

comparison operators and conditional statements (if, elif, else)

i. Comparison Operators - Checking Values in Python
Comparison operators are used to compare two values. They always return a Boolean result (True or False). This is useful when making decisions in code.

age = 20
score = 75

print(age == 20)     # True
print(age == 25)     # False
print(age != 18)     # True
print(score > 20)    # True
print(score < 70)    # False
print(score >= 75)   # True
print(score <= 74)   # False

Output

True
False
True
True
False
True
False

ii. Comparing Strings - Case Sensitivity Matters
String comparisons check if two text values are equal. Python is case-sensitive, so "Data Engineering" is not equal to "data Engineering".

track = "Data Engineering"

print(track == "Data Engineering")
print(track == "data Engineering")
print(track == "Data Science")
print(track != "Data Science")

Output

True
False
False
True

iii. Alphabetical Comparison - Order of Characters
Strings can also be compared alphabetically. Python uses Unicode values, so "A" is less than "C".

print("Amina" < "Collins")   # True, A comes before C
print("Nairobi" == "nairobi") # False, case-sensitive

Output

True
False

iv. Basic if Statement - Single Condition Check
An if statement runs code only when the condition is true. If the condition is false, the block is skipped.

score = 55

if score >= 50:
    print("You passed")      
print("Thank you for taking the test")

Output

You passed
Thank you for taking the test

v. if with else - Two Possible Paths
The else block runs when the if condition is false, giving two possible outcomes.

score = 45

if score >= 50:
    print("Pass well done")
else:
    print("FAIL - Please try again")

print(f"Your Score was {score}")

Output

FAIL - Please try again
Your Score was 45

vi. if-elif-else - Multiple Conditions
elif allows checking multiple conditions in sequence. Order matters — the first true condition is executed.

score = 72

if score >= 80:
    print("Grade A - Excellent")
elif score >= 70:
    print("Grade B - Good")
elif score >= 60:
    print("Grade C - Average")
elif score >= 50:
    print("Grade D - Below Average")
else:
    print("Grade F - Failed")

Output

Grade B - Good

Matatu Ticket Pricing- Example
Conditionals can model real-world systems like fare calculation.

distance = 12

if distance <= 5:
    fare = 30
elif distance <= 15:
    fare = 50
elif distance <= 30:
    fare = 80
else:
    fare = 120

print("=========MATATU FARE========")
print(f"Distance: {distance}km | Fare Ksh{fare}")
print("----------------------------")

Output

text
=========MATATU FARE========
Distance: 12km | Fare Ksh50
----------------------------

vii. Logical Operators - Combining Conditions
Logical operators (and, or, not) let us combine multiple conditions.

• Using and - Both Must Be True

age = 18
has_id = "yes"

if age >= 18 and has_id == "yes":
    print("Access granted - Welcome")
else:
    print("Access denied")

Output

text
Access granted - Welcome

• Using or - At Least One Must Be True

is_student = "yes"
is_senior = "no"

if is_student == "yes" or is_senior == "yes":
    print("Discount applied - 25% off")
else:
    print("No discount")

Output

text
Discount applied - 25% off

Example: Banking - Transaction Limits
Different account types have different limits. Conditionals enforce these rules.

account = "basic"
amount = 80000

if account == "basic" and amount <= 70000:
    print("Transaction Approved")
elif account == "basic" and amount > 70000:
    print("Limit Exceeded for basic account")
elif account == "premium" and amount <= 300000:
    print("Transaction Approved")
else:
    print("Limit exceeded for premium account (max Ksh 300,000)")

Output

Limit Exceeded for basic account

viii. Nested if - Step-by-Step Checks
Nested if allows deeper checks when one condition depends on another.

username = "admin"

if username == "admin":
    password = "kenya2025"
    if password == "kenya2025":
        print("Welcome admin")
    else:
        print("Incorrect password")
else:
    print("User not found")

Output

Welcome admin

Example: Track Enrolled - elif for Alternatives
elif is useful when there are multiple possible paths.

track = "DE"

if track == "DS":
    print("Your next course: Pandas and Numpy")
elif track == "DE":
    print("Your next course: Kafka and Airflow")
else:
    print("Unknown track")

Output

Your next course: Kafka and Airflow

Example: Laptop process - Nested Decision
Here, the second question depends on the first answer.

has_laptop = "yes"
os_type = "Windows"

if has_laptop == "yes":
    if os_type == "Windows":
        print("Install python from python.org")
    else:
        print("Python may already be installed - check with python3 --version")   
else:
    print("Please borrow a laptop for this session")

Output

Install python from python.org

Example: Loan Qualification - Multiple Nested Checks
This example combines several conditions to decide loan eligibility.

has_account = "yes"
months_in = 8
salary = 25000

if has_account == "yes":
    if months_in < 6:
        print("You need at least 6 months of account history")
    else:
        if salary < 20000:
            print("Minimum salary for a loan is Ksh 20000")
        else:
            print("Congratulations! You qualify for a loan")
else:
    print("Sorry, you do not have an account")

Output

Congratulations! You qualify for a loan

Conclusion

Comparison operators check values and relationships.

Conditionals (if, elif, else) control program flow.

Logical operators (and, or) combine conditions.

Nested if allows deeper decision-making.

Order of conditions matters - always put the most specific first.