Programming Basics: Separate Calculation and Display

Split responsibilities into small functions with clear contracts.

All worksheets

5 questions0m 0s

Learn the skill

Define FUNCTION total(price, count): RETURN price * count; END for nonnegative integer inputs. Prices are whole fictional coin units, not real payments. Keep calculation separate from SHOW. Each call returns its own result and changes no outside state.

Worked example

SET cost TO total(4, 3); SHOW cost displays 12. The function can be tested without a screen. A separate caller decides whether, where or how to display the returned value.

The total function multiplies a nonnegative integer price by a nonnegative integer count. Inputs four and three return twelve. The caller stores that return value in cost and SHOW cost displays it.

Would you believe it?

Returning a value is not the same as displaying it. A function can calculate a useful result that its caller stores or uses without showing anything on a screen.

Python documentation: functions

Question 1 What does total(4, 3) return? 43 12 7

Question 2 What does total(4, 0) return? 0 4 An error in every language

Question 3 Which function behavior follows the stated contract? Charge a real card Change an unrelated user's balance Return a number without changing outside state

Question 4 What displays the calculated cost in the example? The parameter names SHOW cost The function definition by itself

Question 5 Why keep calculation separate from display? The result can be tested and reused It guarantees there are no bugs It removes the need for inputs

Review your work

0correct

Complete the questions to review each answer.

View dashboard