SensorReading validReading = new SensorReading(22.5);
SensorReading missingReading = new SensorReading(null);
Console.WriteLine($"Valid reading: {validReading.GetEffectiveTemperature(20.0)}°C");
Console.WriteLine($"Missing reading: {missingReading.GetEffectiveTemperature(20.0)}°C");
public struct SensorReading
{
    public double? TemperatureC { get; }
    public SensorReading(double? temperatureC)
    {
        TemperatureC = temperatureC;
    }
    public double GetEffectiveTemperature(double defaultTemp)
    {
        return TemperatureC ?? defaultTemp;
    }
}