下面是我以前如何将一个浮点数截断到小数点后两位
NSLog(@" %.02f %.02f %.02f", r, g, b);
我查了文档和电子书,但还没找到答案。谢谢!
下面是我以前如何将一个浮点数截断到小数点后两位
NSLog(@" %.02f %.02f %.02f", r, g, b);
我查了文档和电子书,但还没找到答案。谢谢!
当前回答
这里有一个“纯粹的”快速解决方案
var d = 1.234567
operator infix ~> {}
@infix func ~> (left: Double, right: Int) -> String {
if right == 0 {
return "\(Int(left))"
}
var k = 1.0
for i in 1..right+1 {
k = 10.0 * k
}
let n = Double(Int(left*k)) / Double(k)
return "\(n)"
}
println("\(d~>2)")
println("\(d~>1)")
println("\(d~>0)")
其他回答
为什么要把它弄得这么复杂?你可以用这个代替:
import UIKit
let PI = 3.14159265359
round( PI ) // 3.0 rounded to the nearest decimal
round( PI * 100 ) / 100 //3.14 rounded to the nearest hundredth
round( PI * 1000 ) / 1000 // 3.142 rounded to the nearest thousandth
看它在游乐场工作。
PS:解决方案来自:http://rrike.sh/xcode/rounding-various-decimal-places-swift/
use
CGFloat
or
Float.roundTo(places:2)
@infix func ^(left:Double, right: Int) -> NSNumber {
let nf = NSNumberFormatter()
nf.maximumSignificantDigits = Int(right)
return nf.numberFromString(nf.stringFromNumber(left))
}
let r = 0.52264
let g = 0.22643
let b = 0.94837
println("this is a color: \(r^3) \(g^3) \(b^3)")
// this is a color: 0.523 0.226 0.948
Swift2示例:iOS设备的屏幕宽度格式化浮点数去除小数
print(NSString(format: "Screen width = %.0f pixels", CGRectGetWidth(self.view.frame)))
Swift 4 Xcode 10更新
extension Double {
var asNumber:String {
if self >= 0 {
let formatter = NumberFormatter()
formatter.numberStyle = .none
formatter.percentSymbol = ""
formatter.maximumFractionDigits = 2
return "\(formatter.string(from: NSNumber(value: self)) ?? "")"
}
return ""
}
}