2018-10-12 20:35:31 +00:00
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---
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title: Variables
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localeTitle: 变量
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---
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## 变量
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变量将名称与特定类型的值相关联。在Swift中,有两种主要的方法来创建变量。 `let`和`var` 。要声明常量,请使用`let`关键字。要声明可变变量,请使用`var`关键字。
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2018-12-27 00:21:44 +00:00
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Swift中使用两种方式储存变量的好处是防止“改变常量值”这种错误。
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2018-10-12 20:35:31 +00:00
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2018-12-27 00:21:44 +00:00
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```
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let daysInAWeek = 7
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var amountOfMoney = 100
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2018-10-12 20:35:31 +00:00
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amountOfMoney = 150 // amountOfMoney现在是150
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daysInAWeek = 10 //这给了我们一个错误!
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2018-12-27 00:21:44 +00:00
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```
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2018-10-12 20:35:31 +00:00
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在这种情况下,变量`daysInAWeek`应该是常量,因为一周只有七天,而变量`amountOfMoney`应该是var,因为一个帐户中的金额变化。
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常量和变量名称几乎可以包含任何字符,包括Unicode字符:
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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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要测试变量是否具有正确的值,请使用`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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#### 更多信息:
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2018-12-27 00:21:44 +00:00
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* [Swift编程语言](https://docs.swift.org/swift-book/LanguageGuide/TheBasics.html#ID310)
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