以Kotlin字符串模板格式 [英] Format in kotlin string templates

问题描述

Kotlin具有一项出色的功能，称为字符串模板.我真的很喜欢它.

Kotlin has an excellent feature called string templates. I really love it.

 val i = 10 
 val s = "i = $i" // evaluates to "i = 10"

但是模板中可以有任何格式吗?例如，我想在kotlin中格式化字符串模板中的Double格式，至少在小数点分隔符后设置一些数字:

But is it possible to have any formatting in the templates? For example, I would like to format Double in string templates in kotlin, at least to set a number of digits after a decimal separator:

val pi = 3.14159265358979323
val s = "pi = $pi??" // How to make it "pi = 3.14"?

推荐答案

不幸的是，还没有内置的字符串模板格式支持，作为一种变通方法，您可以使用以下方法:

Unfortunately, there's no built-in support for formatting in string templates yet, as a workaround, you can use something like:

"pi = ${pi.format(2)}"

您需要将自己定义为的.format(n)函数

the .format(n) function you'd need to define yourself as

fun Double.format(digits: Int) = "%.${digits}f".format(this)

Kotlin目前显然缺少这里的一项功能，我们将对其进行修复.

There's clearly a piece of functionality here that is missing from Kotlin at the moment, we'll fix it.

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