70 lines
1.5 KiB
Markdown
70 lines
1.5 KiB
Markdown
# Forever
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Keep running part of a program
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[in the background](/reference/control/in-background).
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```sig
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basic.forever(() => {
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})
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```
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### Example: compass
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The following example constantly checks the
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[compass heading](/reference/input/compass-heading)
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and updates the screen with the direction.
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```blocks
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basic.forever(() => {
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let heading = input.compassHeading()
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if (heading < 45) {
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basic.showString("N", 100)
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} else if (heading < 135) {
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basic.showString("E", 100)
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}
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else if (heading < 225) {
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basic.showString("S", 100)
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}
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else {
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basic.showString("W", 100)
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}
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})
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```
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### Example: counter
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The following example keeps showing the [number](/reference/types/number) stored in a global variable.
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When you press button `A`, the number gets bigger.
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You can use a program like this to count things with your BBC micro:bit.
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```blocks
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let num = 0
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basic.forever(() => {
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basic.showNumber(num, 150)
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})
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input.onButtonPressed(Button.A, () => {
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num = num + 1
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})
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```
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### Competing for the LED screen
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If different parts of a program are each trying
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to show something on the LED screen at the same time,
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you may get unexpected results.
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Try this on your micro:bit:
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```blocks
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basic.forever(() => {
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basic.showNumber(6789, 150)
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})
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input.onButtonPressed(Button.A, () => {
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basic.showNumber(2, 150)
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})
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```
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### See also
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[while](/reference/loops/while), [on button pressed](/reference/input/on-button-pressed), [in background](/reference/control/in-background)
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