{
while (true)
{
Console.Write("請輸入x的值：\nx=");
double x = double.Parse(Console.ReadLine());
double y;
const double e = 2.71828;
if (x < 0)
{
y = Math.Log(e, 2);
}
else if (x == 0)
{
y = 1;
}
else
{
y = 1 + Math.Exp(x);
}
Console.WriteLine("y="+y);
}
}