92 lines
2.5 KiB
Markdown
92 lines
2.5 KiB
Markdown
# Local Variables
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How to define and use local variables.
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### @parent language
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A variable is a place where you can store and retrieve data. Variables have a name, a [type](/reference/types), and value:
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* *name* is how you'll refer to the variable
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* *type* refers to the kind of data a variable can store
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* *value* refers to what's stored in the variable
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### Var statement
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Use the Block Editor variable statement to create a variable
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and the [assignment operator](/reference/variables/assign)
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to store something in the variable.
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For example, this code stores the number `2` in the `x` variable:
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```blocks
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let x = 2;
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```
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Here's how to define a variable in the Block Editor:
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1. Click `variables`.
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2. Change the default variable name if you like.
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3. Drag a block type on the right-side of the [assignment operator](/reference/variables/assign) and click the down arrow to change the variable name.
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A variable is created for the number returned by the [brightness](/reference/led/brightness) function.
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```blocks
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let b = led.brightness();
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```
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### Using variables
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Once you've defined a variable, just use the variable's name whenever you need what's stored in the variable. For example, the following code shows the value stored in `counter` on the LED screen:
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```blocks
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let counter = 1;
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basic.showNumber(counter);
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```
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To change the contents of a variable use the assignment operator. The following code sets `counter` to 1 and then increments `counter` by 10:
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```blocks
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let counter = 1;
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counter = counter + 10;
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basic.showNumber(counter);
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```
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### Why use variables?
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If you want to remember and modify data, you'll need a variable.
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A counter is a great example:
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```blocks
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let counter = 0;
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input.onButtonPressed(Button.A, () => {
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counter = counter + 1;
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basic.showNumber(counter);
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});
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```
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### Local variables
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Local variables exist only within the function or block of code where they're defined. For example:
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```blocks
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// x does NOT exist here.
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if (led.brightness() > 128) {
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// x exists here
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let x = 0;
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}
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```
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#### Notes
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* You can use the default variable names if you'd like, however, it's best to use descriptive variable names. To change a variable name in the editor, select the down arrow next to the variable and then click "new variable".
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### Lessons
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[glowing pendulum](/lessons/glowing-pendulum), [love meter](/lessons/love-meter), [temperature](/lessons/temperature), [zoomer](/lessons/zoomer)
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### See also
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[types](/reference/types), [assignment operator](/reference/variables/assign)
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