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Exercise 10 - More Conditional Statements

Goals

  • Write and modify conditional statements
  • Use conditional statements to create branching logic

Preparation

  • You may work with the circuit simulator or a physical circuit
  • Go to Wokwi and create a new CircuitPython project by clicking the button, then choosing CircuitPython on Raspberry Pi Pico
  • Find the button and add a pushbutton to your circuit. It should like something like the circuit below

pi pico and pushbutton

Concepts & Vocabulary

  • Conditional statement
  • if
  • elif
  • else
  • logical test/test condition

Review - Conditional Statements

If

An if statement can be used on its own.

if the condition is true, then do something

if the class is being particularly good, then give each student a brownie

if you are cold, then put on a jacket

if the button is pressed, then turn on the LED

The if statement will do something if the test is true, but will be skipped without any effect if the test is not true

If/Else

An else can be used in combination with an if, but never on its own. You can never have more than one else to go with an if

if the condition is true, then do something

otherwise, do something else

if the class is being particularly good, then give each student a brownie

otherwise, start today's lesson

if you are cold, then put on a jacket

otherwise, go swimming

if the button is pressed, then turn on the LED

otherwise, turn off the LED

If/Elif/Else

The if/else combo above is great if you're checking for something that only has two possible outcomes, either because what you're testing (for instance whether a pushbutton is pressed down) only has two possibilities, or because you're going to have some sort of default, where you do something specific in one circiumstance, and a more generic response in some other circumstance. Sometimes, you need more than two possible outcomes, though, so that's where elif (short for else if) comes in. Look at the following example:

if you are cold, then put on a jacket

otherwise, go swimming

I'm sure you can imagine plenty of possibilities where you wouldn't need to put on a jacket, but also wouldn't want to go swimming. We can rewrite this to be a little more reasonable:

if you are cold, then put on a jacket

otherwise if you are overheated, then put on a swimsuit and go swimming

otherwise relax and hang out with your friends

In code:

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n = random.random()

if n < .5:
  print("small!")
elif n == .5:
  print("right in the middle!")
else:
  print("large!")

Try It

Use one or more buttons to configure settings in your code, rather than directly controlling the button

Examples:

  • Challenging: Use a Neopixel and have a list of colors. Each time you push the button, you cycle through the colors for the Neopixel
  • Challenging: Use two buttons to increase or decrease the blink rate of the LED
  • Moderate: Use a button to determine whether or not the LED blinks
  • Easy: While a button is pressed, increase the blink rate of the LED

Show me your code in action

  • 5 points: successful completion of a challenging example
  • less than 5 points: successful completion of a less challenging example