private int GetFunctionResult(double x)
{
int result=0;
if(x<0)
result=0;
else if(x>=0 &&x<1)
result=1;
else if(x>=1&&x<2)
result=2;
else
result=3;
return result;
}
public static void Main(string[] args)
{
Console.WriteLine("请输入x值");
int result=GetFunciotonResult(Convert.ToDouble(Console.ReadLine()));
Console.WriteLine(result);
}