Swift - 将步幅与 Int 数组一起使用

Question

我想将数字相加并每 4 个元素打印一次，但是我无法使用 stride 函数，如果我使用了错误的方法请解释更好的方法

var numbers = [1,2,3,4,5,6,7,8,9,10,11,12,13]

func addNumbersByStride(){
    var output = Stride...
    //first output = 1+2+3+4 = 10
    //second output = 5+6+7+8 = 26 and so on
    print(output)
}

Answer 1

看来你想使用 stride ...

let arr = [1,2,3,4,5,6,7,8,9,10,11,12,13]

let by = 4
let i = stride(from: arr.startIndex, to: arr.endIndex, by: by)
var j = i.makeIterator()
while let n = j.next() {
    let e = min(n.advanced(by: by), arr.endIndex)
    let sum = arr[n..<e].reduce(0, +)
    print("summ of arr[\(n)..<\(e)]", sum)
}

打印

summ of arr[0..<4] 10
summ of arr[4..<8] 26
summ of arr[8..<12] 42
summ of arr[12..<13] 13