using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"^(?:[A-Z]+//){2}[A-Z]+\K//";
string substitution = @"\\\\";
string input = @"ABC//DEG//IJK//LMN//OPQ//rstuvwxyz
BCA//EGD//JKI//MNL//PQO//stuvwxyzr
ACB//DGE//IJK//LNM//OQP//rstuvwxyz
ABC//DEG//IJK//LMN//OPQ//rstuvwxyz
CAB//GDE//KIJ//NLM//QOP//rstuvwxyz
BAC//EDG//JIK//MLN//POQ//rstuvwxyz";
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