if...else语句的应用

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                Console.WriteLine("请输入您的性别，按回车确认。。。");
                string sex = Console.ReadLine();
                Console.WriteLine("请输入您的身高，按回车确认。。。");
                double height = Convert.ToDouble(Console.ReadLine());
                Console.WriteLine("请输入您的体重，按回车确认。。。");
                double weight = Convert.ToDouble(Console.ReadLine());
                if (sex == "男")
                {
                     if(weight-height+100>-3&&weight-height+100<3)
                     {
                         Console.WriteLine("体重正常。");
                     }
                     else if(weight-height+100<-3)
                     {
                         Console.WriteLine("增加营养。");
                     }
                    else
                     {
                         Console.WriteLine("该减肥了。");
                     }
                }
                else if (sex=="女")
                {
                    if (weight - height + 110 > -3 && weight - height + 110 < 3)
                    {
                        Console.WriteLine("体重正常。");
                    }
                    if (weight - height + 110 < -3)
                    {
                        Console.WriteLine("增加营养。");
                    }
                    else
                    {
                        Console.WriteLine("该减肥了。");
                    }
                }

            }
        }
     }     
}