如何在不使用“.reverse()"的情况下在 Swift 中反转数组? [英] How to reverse array in Swift without using ".reverse()"?

问题描述

我有数组，需要在没有 Array.reverse 方法的情况下反转它，只有一个 for 循环.

I have array and need to reverse it without Array.reverse method, only with a for loop.

var names:[String] = ["Apple", "Microsoft", "Sony", "Lenovo", "Asus"]

推荐答案

这是@Abhinav 的答案翻译成 Swift 2.2 :

Here is @Abhinav 's answer translated to Swift 2.2 :

var names: [String] = ["Apple", "Microsoft", "Sony", "Lenovo", "Asus"]

var reversedNames = [String]()

for arrayIndex in (names.count - 1).stride(through: 0, by: -1) {
    reversedNames.append(names[arrayIndex])
}

使用此代码不会给您任何关于不推荐使用 C 样式 for 循环或使用 -- 的错误或警告.

Using this code shouldn't give you any errors or warnings about the use deprecated of C-style for-loops or the use of --.

Swift 3 - 当前:

let names: [String] = ["Apple", "Microsoft", "Sony", "Lenovo", "Asus"]

var reversedNames = [String]()

for arrayIndex in stride(from: names.count - 1, through: 0, by: -1) {
    reversedNames.append(names[arrayIndex])
}

或者，您可以正常循环并每次减去:

Alternatively, you could loop through normally and subtract each time:

let names = ["Apple", "Microsoft", "Sony", "Lenovo", "Asus"]

let totalIndices = names.count - 1 // We get this value one time instead of once per iteration.

var reversedNames = [String]()

for arrayIndex in 0...totalIndices {
    reversedNames.append(names[totalIndices - arrayIndex])
}

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