// Online C# Editor for free

// Write, Edit and Run your C# code using C# Online Compiler

​

using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main(string[] args)

    {

        string original = "12,\"textt, is\",\"anotther 25,000\",23,\"hello\" tto you";

        Console.WriteLine("Original: " + original);

        Console.WriteLine("Edited:   " + RemoveOrReplaceInsideQuotes(original));

        Console.WriteLine("Ohter:    " + RemoveOrReplaceInsideQuotes(original, "tt", "123"));

    }

    public static string RemoveOrReplaceInsideQuotes(string original, 

                                                     string toRemove = ",", 

                                                     string toReplace = "")

    {

        var regex = new Regex("\".*?\"");

        return regex.Replace(original, s => s.Value.Replace(toRemove, toReplace));

    }

​

}

​