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.
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