44 lines
1.2 KiB
Markdown
44 lines
1.2 KiB
Markdown
---
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title: Variables
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---
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## Variables
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A variable associates a name with a value of a particular type. There are two main ways to create variables in Swift. `let` and `var`. To declare constants use the `let` keyword. To declare mutable variables use the `var` keyword.
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The benefit of having two ways to store variables in Swift is to prevent errors of changing variables that should be constant.
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```Swift
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let daysInAWeek = 7
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var amountOfMoney = 100
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amountOfMoney = 150
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// amountOfMoney is now 150
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daysInAWeek = 10
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// This gives us an error!
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```
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In this case the variable `daysInAWeek` should be a constant because there are only seven days in a week, while the variable `amountOfMoney` should be a var because the amount of money in one's account changes.
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Constant and variable names can contain almost any character, including Unicode characters:
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```Swift
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let π = 3.14159
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let 你好 = "你好世界"
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let 🐶🐮 = "dogcow"
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```
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To test if your variables have the correct value, use `print()`.
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```Swift
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let money = 50
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print(money)
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// This prints 50
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```
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#### More Information:
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* [The Swift Programming Language](https://docs.swift.org/swift-book/LanguageGuide/TheBasics.html#ID310)
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