44 lines
1.2 KiB
Markdown
44 lines
1.2 KiB
Markdown
# While
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Repeat code in a loop while a condition is true. #docs #while #language
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### @parent blocks/language
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Repeat code while a [Boolean](/microbit/reference/types/boolean) `condition` is true.
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### ~hide
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```
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let condition = false
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```
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### ~
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### Block Editor
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The while loop has a *condition* that evaluates to a [Boolean](/microbit/reference/types/boolean) value. After the `do` keyword, add the code that you want to run while the `condition` is `true`. The while loop concludes with `end while`.
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The condition is tested before any code runs. Which means that if the condition is false, the code inside the loop doesn't execute.
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### Example: diagonal line
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The following example uses a while loop to make a diagonal line on the LED screen (points `0, 0`, `1, 1`, `2, 2`, `3, 3`, `4, 4`).
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// index is set to 4
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// subtract 1 from `index` each time through loop
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### Lessons
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[rotation animation](/microbit/lessons/rotation-animation)
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### See also
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[on button pressed](/microbit/reference/input/on-button-pressed), [for](/microbit/reference/loops/for), [if](/microbit/blocks/if), [forever](/microbit/reference/basic/forever)
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