圆形加倍到0.5

Question

我有一个结果"1.444444",我想将此结果舍入到"1.5"这是我使用的代码:

a.text = String(round(13000 / 9000.0))

但这是圆的"1.0",我需要圆到"1.5"

而这段代码:

a.text = String(ceil(13000 / 9000.0))

圆到"2.0"

Answer 1

斯威夫特3:

extension Double {
    func round(nearest: Double) -> Double {
        let n = 1/nearest
        let numberToRound = self * n
        return numberToRound.rounded() / n
    }

    func floor(nearest: Double) -> Double {
        let intDiv = Double(Int(self / nearest))
        return intDiv * nearest
    }
}

let num: Double = 4.7
num.round(nearest: 0.5)      // Returns 4.5

let num2: Double = 1.85
num2.floor(nearest: 0.5)     // Returns 1.5

斯威夫特2:

extension Double {
    func roundNearest(nearest: Double) -> Double {
        let n = 1/nearest
        return round(self * n) / n
    }
}

let num: Double = 4.7
num.roundNearest(0.5)      // Returns 4.5

Answer 2

x = 13000 / 9000.0;

denominator = 2;
a.text = String(round(x*denominator )/denominator );

首先将1.444转换为2.888,然后舍入为3.0,然后除以2得到1.5.在这种情况下,0.5的分母是2(即1/2).如果要舍入到最接近的四分之一(0.25,0.5,0.75,0.00),则分母= 4

我应该指出,如果分母是2的幂,这是完美的.如果它不是denominator=3,那么你可以得到奇怪的答案,如1.99999999而不是2的特定值.