使用Regex.Replace（）将cm转换为mm

I want to take the following input <tag>30.234234cm</tag> and get the following output <tag>302.34234mm</tag>. Where the value between the tags is a value in centimetres that may be decimal or integer, and the goal is to convert that value to millimetres.

我想采用以下输入 30.234234cm 并获得以下输出 302.34234mm 。标签之间的值是以厘米为单位的值,可以是十进制或整数,目标是将该值转换为毫米。

var input = "<tag>30.234234cm</tag>";
input = Regex.Replace(input, @"(\d+(\.\d+)?)cm", (double.Parse("$1") * 10).ToString() + 
    "mm", RegexOptions.IgnoreCase);

I am using the expression (\d+(\.\d+)?) for the first capture group. However, $1 will not work in the context of double.Parse($1). How can I get the value of the unit, convert it and replace it in the example string provided?

我正在使用表达式(\ d +(\。\ d +)?)作为第一个捕获组。但是,$ 1在double.Parse($ 1)的上下文中不起作用。如何获取单元的值,转换它并在提供的示例字符串中替换它?

2 个解决方案

#1

Well,

  double.Parse("$1")

tries to parse "$1" constant string and fails. I suggest using lambda:

尝试解析“$ 1”常量字符串并失败。我建议使用lambda:

  var input = "<tag>30.234234cm</tag>";

  input = Regex.Replace(
      input, 
     @"(\d+(\.\d+)?)cm", 
      match => (double.Parse(match.Groups[1].Value) * 10).ToString() + "mm",
      RegexOptions.IgnoreCase);

Here match.Groups[1].Value is a value of the captured group (30.234234 in the example)

这里match.Groups [1] .Value是捕获组的值(示例中为30.234234)

#2

You're using "(\d+(\.\d+)?)cm" with "cm" as a capture, because of that you can't perform `double.Parse("$1")

你使用“(\ d +(\。\ d +)?)cm”和“cm”作为捕获,因为你不能执行`double.Parse(“$ 1”)

#1