float number = float.Parse("0,54"); // it works well, but
float number = float.Parse("0.54"); // gains exepction.

int begin = 0;
int end = 0;
for (int i = 0; i < tempLine.Length; i++)
{
    if (Char.IsWhiteSpace(tempLine.ElementAt(i)))
    {
        end = i;
        float value = float.Parse(tempLine.Substring(begin, end));
        begin = end;
        System.Console.WriteLine(value);
    }
}

float number = float.Parse("0.54", CultureInfo.InvariantCulture);

var culture = (CultureInfo)CultureInfo.CurrentCulture.Clone();
culture.NumberFormat.NumberDecimalSeparator = ".";
float number = float.Parse("0.54", culture);

var value = float.Parse(tempLine.Substring(begin, end), CultureInfo.InvariantCulture);

foreach(var str in tempLine.Split())
{
    float value = float.Parse(str, CultureInfo.InvariantCulture);
}