如何在swift[duplicate]中获得1个十进制浮点值

Question

我想从现有的浮点数中提取1个十进制浮点数。

我在Objective-C中做过：使浮点只显示两位小数

知道如何在Swift中实现吗？

Answer 1

中缀运算符怎么样？

// Declare this at file level, anywhere in you project. 
// Expressions of the form 
//     "format string" %% doubleValue
// will return a string. If the string is not a well formed format string, you'll
// just get the string back! If you use incorrect format specifiers (e.g. %d for double)
// you'll get 0 as the formatted value.
operator infix %% { }
@infix func %% (format: String, value: Double) -> String {
    return NSString(format:format, value)
}

// ...
// You can then use it anywhere
let experience = 1.234
println("Pro Forma:- \n Total Experience(In Years) = %.01f" %% experience)

我试图用泛型来做这件事，但我不知道怎么做。要使它适用于多种类型，只需为这些类型重载它-例如。

operator infix %% { }
@infix func %% (format: String, value: Double) -> String {
    return NSString(format:format, value)
}
@infix func %% (format: String, value: Float) -> String {
    return NSString(format:format, value)
}
@infix func %% (format: String, value: Int) -> String {
    return NSString(format:format, value)
}

Answer 2

你可以试试这个

var experience = 10.25
println("Pro Forma:- \n Total Experience(In Years) = " + NSString(format: "%.01f", experience))

Answer 3

您可以快速制作相同的：

var formatter : NSString = NSString(format: "%.01f", myFloat)

或者像你想在一行：

println("Pro Forma:- \n Total Experience(In Years) = "+(NSString(format: "%.01f", myFloat)))

这也适用于旧的NSLog（但更喜欢println）：

NSLog("Pro Forma:- \n Total Experience(In Years) = %.01f \n", myFloat)