using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(xyz(?:(?!abc).)*?)123";
string substitution = @"$1456";
string input = @"abc----1
pqr----2
123----3
xyz----4
lll----5
pqr----6
123----7
qqq----8
xyz----5
abc----3
123----9";
RegexOptions options = RegexOptions.Multiline | RegexOptions.Singleline;
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