如何在Swift中添加两个通用值? [英] How do I add two generic values in Swift?

问题描述

我正在尝试编写一个将数字类型数组求和的函数.据我所知:

I am trying to write a function to sum an array of numeric types. This is as far as I got:

protocol Numeric { }
extension Float: Numeric {}
extension Double: Numeric {}
extension Int: Numeric {}

func sum<T: Numeric >(array:Array<T>) -> T{
    var acc = 0.0
    for t:T in array{
        acc = acc + t
    }
    return acc
}

但是我不知道如何在 Numeric 协议中定义 + 运算符的行为.

But I don't know how to define the behaviour of the + operator in the Numeric protocol.

推荐答案

protocol Numeric {
    func +(lhs: Self, rhs: Self) -> Self
}

应该足够了.

来源: http://natecook.com/blog/2014/08/generic-functions-for-incompatible-types/

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