using System.Globalization;
public static void Main()
NumberFormatInfo provider = new NumberFormatInfo();
provider.NumberDecimalDigits = 2;
provider.NumberDecimalSeparator = ",";
provider.NumberGroupSeparator = ".";
provider.NumberGroupSizes = new int[] { 3 };
string strValue = "1.799,53";
double result = Convert.ToDouble(strValue, provider);
Console.WriteLine(result.ToString());
result = Convert.ToDouble(strValue, provider);
Console.WriteLine(result.ToString());
result = Convert.ToDouble(strValue, provider);
Console.WriteLine(result.ToString());
result = Convert.ToDouble(strValue, provider);
Console.WriteLine(result.ToString());