正则表达式(C#):将\n替换为\ r \n

using System;
using System.Text.RegularExpressions;

class Program
{
    static void Main(string[] args)
    {
        string input = "This is a sample text.\nIt contains newline characters.\n";
        string pattern = @"\n";
        string replacement = @"\r\n";
        string result = Regex.Replace(input, pattern, replacement);

        Console.WriteLine(result);
    }
}