4. Making decisions with if/else

A condition is a question that Python answers with either True or False. You write conditions using comparison operators:

== equal to (5 == 5 → True)

!= not equal to (5 != 3 → True)

> greater than (10 > 7 → True)

< less than (3 < 1 → False)

>= greater or equal (5 >= 5 → True)

<= less or equal (4 <= 3 → False)

Notice the double equals == for comparison. A single = stores a value (assignment); a double == asks a question ("are these the same?"). Mixing them up is the most common beginner mistake.

Examples with Ethiopian context:

balance = 200 # balance in birr

price = 150

print(balance > price) # True — enough money

print(balance == price) # False — amounts differ

An if statement runs a block of code only when a condition is True. The structure is:

if condition:

# code to run when condition is True

The colon : at the end of the if line is required — it signals that a block of code follows. That block must be indented (4 spaces is standard). Python uses indentation to know which lines belong to the if:

age = 20

if age >= 18:

print("You can open a TeleBirr account.")

print("Thank you for visiting.")

Here, the first print is inside the if (indented) — it only runs when age is 18 or more. The second print is outside the if (not indented) — it always runs.

If age = 15, only "Thank you for visiting." is printed. The indented line is skipped.

An if statement alone only handles the True case. To handle both outcomes — True and False — you add an else:

if condition:

# runs when condition is True

else:

# runs when condition is False

Example — a simple TeleBirr balance check:

balance = 80

price = 150

if balance >= price:

print("Payment approved. Thank you!")

else:

print("Insufficient balance. Please top up.")

Output (because 80 < 150):

Insufficient balance. Please top up.

The else block runs when the if condition is False. Only one of the two blocks ever runs — Python chooses based on the condition.

Change balance to 200 and rerun the program — now the first message appears instead.

Sometimes you need more than two outcomes. elif (short for "else if") lets you check additional conditions in sequence:

if condition1:

# runs if condition1 is True

elif condition2:

# runs if condition1 is False AND condition2 is True

elif condition3:

# runs if condition1 and condition2 are False AND condition3 is True

else:

# runs if ALL conditions above are False

Python checks conditions from top to bottom and stops at the first True one. Only that block runs.

Example — a school grade system used in Addis Ababa:

score = 74

if score >= 90:

print("Grade: A — Excellent!")

elif score >= 80:

print("Grade: B — Very Good")

elif score >= 70:

print("Grade: C — Good")

elif score >= 50:

print("Grade: D — Pass")

else:

print("Grade: F — Fail")

Output:

Grade: C — Good

With score = 74, the first two conditions (>= 90 and >= 80) are False, but >= 70 is True, so "Grade: C" is printed. The remaining elif and else are ignored.

Conditions in Python evaluate to Boolean values — True or False (capital T and F, they are keywords). You can store Boolean values in variables:

is_registered = True

has_balance = False

You can also combine conditions with logical operators:

and — both conditions must be True

or — at least one condition must be True

not — flips True to False and vice versa

Examples:

age = 25

has_id = True

if age >= 18 and has_id:

print("Abebe can open an account.")

discount = True

vip = False

if discount or vip:

print("Special price applies.")

shop_open = False

if not shop_open:

print("The shop is closed. Come back tomorrow.")

Logical operators let you express real-world rules in one clean if statement instead of using confusing nested ifs.