85 lines
2.7 KiB
Markdown
85 lines
2.7 KiB
Markdown
# Number
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An integer number.
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### @parent js/language
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A *Number* is an integer such as `42` or `-42`. More precisely, a *Number* is a signed 32-bit integer (two's complement).
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### Declare a number variable
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Use the [var statement](/reference/variables/var) and the [assignment operator](/reference/variables/assign) `:=` to declare a *local* number variable. Like this:
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```
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let number1 = 2
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let number2 = 2
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```
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To declare a *global* number variable, see [global variables](/js/data).
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### Arithmetic operators
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The following arithmetic operators work on numbers and return a [Number](/reference/types/number):
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* addition: `1 + 3`
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* subtraction: `1 - 3 `
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* multiplication: `3 * 2`
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* integer division: `7 / 3`
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* modulo is available through the [math library](/js/math)
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### Relational operators
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The following relational operators work on numbers and return a [Boolean](/reference/types/boolean):
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* equality: `(3 + 1) = 4`
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* inequality: `3 != 4`
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* less or equal than: `3 <= 4`
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* less than: `3 < 4`
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* greater or equal than : `4 >= 3`
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* greater than: `4 > 3`
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### Show number
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The [show number](/reference/basic/show-number) function displays a number on the [LED screen](/device/screen). For example, this code displays the number 42:
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```
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basic.showNumber(42, 100)
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```
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### Functions that return a number
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Some functions return a number, which you can store in a variable. For example the following code gets the display brightness (using the [brightness function](/reference/led/brightness)) and stores the value in a variable named `brightness`:
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```
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let brightness = led.brightness()
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```
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### Math functions
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The [math library](/js/math) includes math related functions. In the [Touch Develop editor](/js/editor), click `math` on the Code Keyboard to see the math functions. For example, the `mod` function returns the modulus (division of one number by another number):
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```
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number1 = math.mod(4, 3)
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```
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### Convert a number to a string
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The `to string` function converts a Number into a [String](/reference/types/string). The following code converts `number1` to a string and stores the string in the `str` variable:
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```
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let str = number1.toString()
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```
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### Bit-level manipulation
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The [bits library](/js/bits) includes functions for bit-level manipulation of integers. In the [Touch Develop editor](/js/editor), click `bits` on the Code Keyboard to see these functions.
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### Lessons
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[counter](/lessons/counter), [love meter](/lessons/love-meter), [flipping bird](/lessons/flipping-bird), [catch the egg game](/lessons/catch-the-egg-game)
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### See also
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[math library](/js/math), [var](/reference/variables/var), [bits library](/js/bits), [Boolean](/reference/types/boolean), [show number](/reference/basic/show-number)
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