字典初始化方式之间的差异 [英] Differences between ways of initializing a dictionary

问题描述

我正在学习Swift，并且想知道初始化空字典的这些方式之间有什么区别?

I'm learning Swift and was wondering what the differences were between these ways of initializing an empty dictionary?

var emptyDic = Dictionary<String, String>()

var emptyDic:[String:String] = [:]

var emptyDic = [String:String]()

这将:

var emptyDic:[String:String]

创建未初始化的字典吗?

create an un-initialized dictionary?

谢谢！

推荐答案

示例1和3在语法上几乎是等效的，因为第3个是第一个的简写.但是在声明1、2和3后，它们在语义上是相同的.因此，与其说是巨大的差异，不如说是个人喜好(对我来说是第三个:).

Example 1 and 3 are almost syntactically equivalent since the 3rd one is a shorthand notation of the first. But after the declaration of 1, 2 and 3 they are semantically the same. So it is more a personal preference (for me the 3rd one :) rather than a huge difference.

但是第四个示例(如您所说)尚未初始化，如果您过早访问它，编译器会警告您.

However the 4th example is (as you said) uninitialized and the compiler will warn you if you want to access it too early.

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