How to check if object is nullabla to set text on the label xamarin

Issue

I have a double? object and want when He has no value to set text on label "0 mm".

I try like this but not work for me:

double? test = weatherBindingData.WeatherDataForecastHourly.List[0].SnowForecast.SnowForecastValue;

        if (!test.HasValue)
        {
            SnowForecast1Day.Text = "0 mm";
        }

Solution

double? test = some value or null;
string str = test?.ToString("0.00 mm") ?? "0 mm";

Answered By - MrMoeinM