小编AWS*_*Mpb的帖子

我最近开始通过在线课程快速学习。

我被赋予了从包含字符的给定数组中生成密码的任务。我们主要学习了两个代码示例，随机选择一个。

1. variable[Int.random(in: 0...25)]
2. variable.randomElement()

当从数组中拉出一个元素时，两者都可以正常工作，但variable[Int.random(in: 0...25)在多次与加号 (+) 组合时只能使用“ ”。

这是为什么？

我查阅了文档但找不到答案

https://developer.apple.com/documentation/swift/array/2994747-randomelement

解释：

此代码有效：

let alphabet = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

//The number of letters in alphabet equals 26
var password = alphabet[Int.random(in: 0...25)] + alphabet[Int.random(in: 0...25)] + alphabet[Int.random(in: 0...25)] + alphabet[Int.random(in: 0...25)] + alphabet[Int.random(in: 0...25)] + alphabet[Int.random(in: 0...25)]  

print(password)

此代码不起作用，因为“randomElement()”在将多个与加号组合后变灰（为什么？）

let alphabet = ["a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"]

//The number of letters in alphabet equals 26
var password = alphabet.randomElement() + alphabet.randomElement() + alphabet.randomElement() + alphabet.randomElement() + alphabet.randomElement() + alphabet.randomElement()  

print(password)

编辑：感谢您的快速解释！