using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        string valueDev = "10.1";

        float receivedValue;

        bool valueParseable = float.TryParse(valueDev, NumberStyles.Float, CultureInfo.InvariantCulture, out receivedValue);

        string driftValue = "0.1";

        float drift = float.Parse(driftValue, CultureInfo.InvariantCulture);

        float targetValueDriver = receivedValue + drift;

        float targetValueDec = (float)((decimal)receivedValue + (decimal)drift);

        Console.WriteLine(receivedValue);

        Console.WriteLine(drift);

        Console.WriteLine(targetValueDriver);

        Console.WriteLine(targetValueDriver.ConvertToStr());

        Console.WriteLine(targetValueDec);

        Console.WriteLine(targetValueDec.ConvertToStr());

    }

}

​

public enum DecimalSeparator

  {

    /// <summary>Example: "0,5"</summary>

    Comma,

    /// <summary>Example: "0.5"</summary>

    Dot,

  }

​

public static class Extension

{

    public static string ConvertToStr(

      this float value,

      string format = "R",

      DecimalSeparator decimalSeparator = DecimalSeparator.Dot)

    {

      NumberFormatInfo numberFormatInfo = new NumberFormatInfo()

      {

        CurrencyDecimalSeparator = decimalSeparator.ToString(),

        NumberGroupSeparator = "",

        CurrencyGroupSeparator = ""

      };

      return value.ToString(format, (IFormatProvider) numberFormatInfo);

    }

}