pxt-calliope/docs/reference/js/lessons/compare-machine/challenges.md
2016-03-25 16:47:20 -07:00

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compare machine challenges

These challenges allow you to set the value of a counter to 1 when button B is pressed. #docs

Challenge 0

Welcome! This guided tutorial will assist you with using the comparison operator.

counter = 0
input.onButtonPressed("A", () => {
    counter = counter + 1
    if (counter == 10) {
        counter = 1
    }
    basic.showNumber(counter, 150)
})

Challenge 1

Now let's do something special when the micro:bit reaches the number 5. Instead of just showing the number 5, let's show the string HALF WAY!. Begin by setting an if statement to know when counter = 5.

counter = 0
input.onButtonPressed("A", () => {
    counter = counter + 1
    if (counter == 10) {
        counter = 1
    }
    if (counter == 5) {
    }
    basic.showNumber(counter, 150)
})

Challenge 2

Let's continue our plan of displaying HALF WAY! when counter = 5. To do so, add the following line of code inside the if statement.

counter = 0
input.onButtonPressed("A", () => {
    counter = counter + 1
    if (counter == 10) {
        counter = 1
    }
    if (counter == 5) {
        basic.showString("HALF WAY!", 150) // ***
    }
    basic.showNumber(counter, 150)
})
  • Run your code to see if it works as expected.

Challenge 3

You may notice a problem right now. When counter = 5, the micro:bit will show both the message HALF WAY! and the number 5. In order to fix this problem, let's take advantage of the else at the end of the if statement.

counter = 0
input.onButtonPressed("A", () => {
    counter = counter + 1
    if (counter == 10) {
        counter = 1
    }
    if (counter == 5) {
        basic.showString("HALF WAY!", 150)
    } else {
        basic.showNumber(counter, 150) // ***
    }
})

Challenge 4

When counter = 8, display the message ALMOST THERE! on the micro:bit. You will need to add an else if after the if statement of counter = 5.