如何快速复制数组的结尾? [英] How to copy end of the Array in swift?

问题描述

一定有一些非常优雅的方式使用 Swift 从某个索引开始复制数组的结尾，但我找不到它，所以我以这个结束:

There must be some really elegant way of copying end of the Array using Swift starting from some index, but I just could not find it, so I ended with this:

func getEndOfArray<T>( arr : [T], fromIndex : Int? = 0) -> [T] {
    var i=0;
    var newArray : [T] = [T]()
    for item in arr {
        if i >= fromIndex {
            newArray.append(item)
        }
        i = i + 1;
    }
    return newArray // returns copy of the array starting from index fromIndex
}

在没有额外功能的情况下，有没有更好的方法来做到这一点?

Is there a better way of doing this without extra function?

推荐答案

还有一个...

let array = [1, 2, 3, 4, 5]
let fromIndex = 2
let endOfArray = array.dropFirst(fromIndex)
print(endOfArray) // [3, 4, 5]

这给出了一个 ArraySlice 对于大多数人来说应该足够好目的.如果你需要一个真正的Array，使用

This gives an ArraySlice which should be good enough for most purposes. If you need a real Array, use

let endOfArray = Array(array.dropFirst(fromIndex))

如果起始索引大于(或等于)元素计数，则创建一个空数组/切片.

An empty array/slice is created if the start index is larger than (or equal to) the element count.

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