pxt-calliope/docs/reference/js/lessons/compare-machine/challenges.md

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2016-03-26 00:47:20 +01:00
# 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](/microbit/lessons/comparison/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`.