using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(\d+\.([1-9]{3}|[1-9]{2}|[1-9]|0{1}))(\d*)";
string input = @"#提取有效小数的思路：匹配出符合要求的组合不符合要求的组。
#使用sub函数，re.sub(pat,lambda m:m[1],s)
#repl使用函数，传递的参数是pat,所匹配的match对象，提取match对象中符合要求的组即可。
124.1230000012
124.1200003412
123.0000000012
1.2000
";
RegexOptions options = RegexOptions.Multiline;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx