Choose Between Two Paths

An if statement can run a block when its condition is true. When the condition is false, Python skips that block and continues.

Sometimes a program must choose exactly one of two paths. An else block provides the second path.

A choice with two outcomes

Run this example:

Python evaluates temperature < 10 once.

• If the condition is True, the first indented block runs.

• If the condition is False, the else block runs.

Exactly one of those two blocks runs. The final print call is outside both blocks, so it runs afterward in either case.

Change temperature to 16 and run the example again. The first message is skipped and the else message appears.

How if and else line up

The if and else keywords must have the same indentation:

if condition:
    # Runs when the condition is true
else:
    # Runs when the condition is false

The colon after else is required. else does not have its own condition because it means “in every other case.”

This is not valid Python:

else temperature >= 10:

If you need to check another condition, you will learn the elif keyword in the next lesson.

Use else instead of asking the opposite question

You could write two separate decisions that ask opposite questions:

For a true two-way choice, if and else express the relationship more clearly:

The second version asks one question and guarantees one result. It also avoids the risk of changing one comparison later but forgetting to update its opposite.

Store a result in each branch

Branches can assign different values to the same variable:

Whichever branch runs assigns a string to booking_status. The print call comes after the complete decision and uses the value chosen by that branch.

This pattern is useful when the program needs to choose data first and display or use it afterward.

A Boolean variable works here too

The condition can be a Boolean variable:

There is no need to write notifications_enabled == True. The variable already contains the Boolean answer.

# Version A
if score >= 50:
    print("Passed")
    else:
        print("Try again")

# Version B
if score >= 50:
    print("Passed")
else:
    print("Try again")

points = 7
if points >= 10:
    print("Target reached")
else:
    print("Keep going")
print("Checked")

Build a booking message

The exercise gives you a fixed number of remaining seats. Use one if/else statement to assign booking_message:

• use Seats are available. when seats_remaining is greater than 0;

• otherwise, use Sold out..

The supplied print calls display the chosen message and then confirm that the check is complete. After your solution passes, change seats_remaining to a positive number and run it again to see the other path.