在下面的代码块中,我无法理解let x其中x.hasSuffix(“pepper”).
let vegetable = "red pepper"
switch vegetable {
case "celery":
let vegetableComment = "Add some raisins and make ants on a log."
case "cucumber","watercress":
let vegetableComment = "That would make a good tea sandwhich"
case let x where x.hasSuffix("pepper"):
let vegetableComment = "Is it a spicy \(x)"
default:
let vegetableComment = "Everything tastes good in soup."
}
Console output
vegetableComment: Is it a spicy red pepper
似乎发生了以下逻辑.
x = vegetable
if (x's suffix == 'pepper')
run case
有人能帮我解释一下吗？
vegetable是一个隐式String.它和你写的一样：
var vegetable: String = "red pepper"
hasSuffix声明为func hasSuffix(后缀：String) – > Bool因此返回Bool. where关键字指定其他要求,并且只能在switch语句中使用.
因为所有这些都是泛滥的,所以将vegetable变量赋给x(let x).
您可以阅读有关where的更多信息并切换here.
