using System.Text.RegularExpressions;
public static void Main()
string pattern = "(?!(([^\"]* \"){2})*[^\"]*$)\n+";
string replaceBy = " A ";
string origenWithQuotes = "\"Mustafa Kemal \n Pasa CD No 15;\"IST_TURKIA2\" \"Mustafa \n Kemal Pasa CD No 15 \";\"IST_TURKIA2\"";
string origenWithoutQuotes = "Mustafa Kemal \n Pasa CD No 15;IST_TURKIA2 \"Mustafa Kemal Pasa CD No 15 \";\"IST_TURKIA2\"";
Console.WriteLine("String with Quotes -> " + new Regex(pattern).Replace(origenWithQuotes, replaceBy));
Console.WriteLine("String without Quotes -> " + new Regex(pattern).Replace(origenWithoutQuotes, replaceBy));
Console.WriteLine("String with Quotes Function -> " + RegeReplace(origenWithQuotes,pattern,replaceBy));
Console.WriteLine("String without Quotes Function -> " + RegeReplace(origenWithoutQuotes,pattern,replaceBy));
Console.WriteLine("Working");
Console.WriteLine("String with Quotes Function -> " + Regex.Replace(origenWithQuotes, @"\""[^\""]*?[\n\r]+[^\""]*?\""", m=>Regex.Replace(m.Value,@"[\n\r]","X")));
Console.WriteLine("String with Quotes Function -> " + Regex.Replace(origenWithoutQuotes, @"\""[^\""]*?[\n\r]+[^\""]*?\""", m=>Regex.Replace(m.Value,@"[\n\r]","X")));
public static String RegeReplace(string Origen, string Patron, string ReemplazarPor)
Regex rgx = new Regex(Patron);
NuevaCadena = rgx.Replace(Origen, ReemplazarPor);