.NET Fiddle

CSharp · Console

/Program.cs

using System;
using System.Text.RegularExpressions;
					
public class Program
{
	public static void Main()
	{
		var r = new Regex("(.*)");
		var c = "XYZ";
		var uc = r.Replace(c, "A $1 B");
		
		Console.WriteLine(uc);
	}
}