in Hands-on lab/lab-files/starter-project/CloudToDevice/Program.cs [90:106]
private static double GetReadLineDouble(String msg, double min, double max)
{
bool valid = false;
double value = 0;
Console.WriteLine();
do
{
Console.Write(msg);
Console.WriteLine();
double.TryParse(Console.ReadLine(), out value);
if (value >= min && value <= max)
valid = true;
} while (!valid);
return value;
}