舍入到2位小数位 [英] Round up double to 2 decimal places

问题描述

如何将 currentRatio 整理为两位小数位？

How do I round up currentRatio to two decimal places?

let currentRatio = Double (rxCurrentTextField.text!)! / Double (txCurrentTextField.text!)!
railRatioLabelField.text! = "\(currentRatio)"

推荐答案

字符串可以舍入到两位小数，并将 double 转换为 String ：

Use a format string to round up to two decimal places and convert the double to a String:

let currentRatio = Double (rxCurrentTextField.text!)! / Double (txCurrentTextField.text!)!
railRatioLabelField.text! = String(format: "%.2f", currentRatio)

示例：

let myDouble = 3.141
let doubleStr = String(format: "%.2f", myDouble) // "3.14"

如果你想对最后一个小数位进行舍入，你可以这样做（感谢Phoen1xUK）：

If you want to round up your last decimal place, you could do something like this (thanks Phoen1xUK):

let myDouble = 3.141
let doubleStr = String(format: "%.2f", ceil(myDouble*100)/100) // "3.15"

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