using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"([^\s]*\s*)\\rem\{(?:lp|db)\}(\{((?>[^{}]|\n|(?2))*)\})(\s?[^\s]*)";
string substitution = @"$1\\textcolor{red}{\\underline{<<ReTe>>}}$4";
string input = @"
Some text etc word\rem{lp}{ more text {\ce{O2}} further text {\ce{H2O}} . some other text the $m = 48$ ({\ce{O2}}) ps}.
\rem{lp}{ more text {\ce{O2}} further text {\ce{H2O}} . some other text the $m = 48$ ({\ce{O2}}) ps
where more text {\ce{O2}} further text {\ce{H2O}} . some other text the $m = 48$ ({\ce{O2}}) ps from
who more text {\ce{O2}} further text {\ce{H2O}} . some other text the $m = 48$ ({\ce{O2}}) ps.}
\rem{lp}{ more text {\ce{O2}} further text {\ce{H2O}} . some other text the $m = 48$ ({\ce{O2}}) ps.
more text {\ce{O2}} further text {\ce{H2O}} . some other text the $m = 48$ ({\ce{O2}}) ps.}
\subsection{other}
Our bla bla bla";
RegexOptions options = RegexOptions.Multiline;
Regex regex = new Regex(pattern, options);
string result = regex.Replace(input, substitution);
}
}
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