林鼎棋 林鼎棋 - 4 months ago 32
Swift Question

How to get the Power of some Integer in Swift language?

I'm learning swift recently, but I have a basic problem that can't find an answer

I want to get something like

var a:Int = 3
var b:Int = 3
println( pow(a,b) ) // 27


but the pow function can work with double number only, it doesn't work with integer, and I can't even cast the int to double by something like Double(a) or a.double()...

Why it doesn't supply the power of integer? it will definitely return an integer without ambiguity !
and Why I can't cast a integer to a double? it just change 3 to 3.0 (or 3.00000... whatever)

if I got two integer and I want to do the power operation, how can I do it smoothly?

Thanks!

Answer

If you like, you could declare an infix operator to do it.

// Put this at file level anywhere in your project
infix operator ^^ { associativity left precedence 160 }
func ^^ (radix: Int, power: Int) -> Int {
    return Int(pow(Double(radix), Double(power)))
}

// ...
// Then you can do this...
let i = 2 ^^ 3
// ... or
println("2³ = \(2 ^^ 3)") // Prints 2³ = 8

I used two carets so you can still use the XOR operator.