什么样的类型在for循环中有范围?

What kind of type have the range in for loop?(什么样的类型在for循环中有范围?)

问题描述

当我们编写以下内容时:

When we write the following:

for i in 1...10 {
//do stuff
}

我想知道在函数调用中使用范围 1...10 的类型，例如:

I want know what type have the range 1...10 to use it in function call for example:

myFunc(1...10)

推荐答案

如果你在定义let range = 1..<10之后下一个断点，你会发现其实不是Range 结构，但评估一个 CountableRange(或 CountableClosedRange 表示 0...10)

If you put a breakpoint after defining let range = 1..<10, you will see that it's actually not a Range structure, but rater a CountableRange (or CountableClosedRange for 0...10)

文档:CountableRange、CountableClosedRange

功能:

func printRange(range: CountableRange<Int>) {
    for i in range { print ("(i)") }
}

func printRange(range: CountableClosedRange<Int>) {
    for i in range { print ("(i)") }
}

用法:

let range = 1..<10
printRange(range: range)

let closedRange = 1...10
printRange(range: closedRange)

通用函数:

由于两个结构都符合 RandomAccessCollection 协议，因此您只能像这样实现一个功能:

Since both structs conform to RandomAccessCollection protocol, you can implement only one function like this:

func printRange<R>(range: R) where R: RandomAccessCollection {
    for i in range { print ("(i)") }
}

这篇文章关于 Swift 3 中的范围也可能有用.

This article about ranges in Swift 3 may also be useful.

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