Question

我在这里有一种进入星期几的方式，但如果我输入的数字值不是1-7，程序就会结束。我想有办法触发捕获。

        namespace DaysOfTheWeek
{
class Program
{
    public enum EDay
    {
        Monday,
        Tuesday,
        Wednesday,
        Thursday,
        Friday,
        Saturday,
        Sunday,
    }
    static void Main(string[] args)
    {
        try
        {
            Console.WriteLine("Hello!  A week has 7 days!  What day of this week is it?");
            EDay pickDay = (EDay)Enum.Parse(typeof(EDay), Console.ReadLine(), true);
            Console.WriteLine("The day you picked was {0}", pickDay - 1);
            Console.ReadLine();
        }
        catch (Exception)
        {
          Console.WriteLine("Please enter an actual numerical day of the week.");
            Console.ReadLine();
        }
    }

}

}

Answer 1

您可以使用IsDefined()之类的

  $connection->query('xdrop procedure if exists parents');
  $connection->query('
   create procedure parents(in parent int(11),in name varchar(22))
   begin
    set @parent=parent;
    drop temporary table if exists ids;
    create temporary table ids(id int(11));
    while @parent<>0 do
     prepare statement from concat("select related into @parent from ",name," where id=?");
     execute statement using @parent;
     insert into ids(id) values(@parent);
    end while;
    select*from ids;
   end;
  ');
  $connection->query('drop function if exists counted');
  $connection->query('
   create function counted(parent int(11),name varchar(22))
   returns int(11)
   begin
    call parents(parent,name);
    return (select count(*) from ids);
   end;
   ');
   $fetch=$connection->query('select counted(3,"category");')->fetchall();

Answer 2

如果输入预期为“数字”，则应使用int.Parse。并且，int.TryParse将帮助您捕获无数字输入：

var input = Console.ReadLine();
if (int.TryParse(input, out var value))
{
    if (1 <= value && value <= 7)
    {
        Console.WriteLine("The day you picked was {0}", (EDay)value - 1);
    }
    else
    {
        Console.WriteLine("PLease enter an number between 1 - 7");
    }
}
else
{
    Console.WriteLine("Please enter an actual numerical day of the week.");
}

如果您还希望接受“monday”之类的输入并添加数值，也可以使用Enum.TryParse。如果您希望1映射到Monday：

，请务必更改此行

Monday = 1,

如果您对(EDay)value解决方案进行了上述更改，也可以直接使用int.TryParse。

Answer 3

在将其转换为枚举之前，您可能希望首先阅读他们输入的内容。

这是一个简单的例子：

try
{
    Console.WriteLine("Hello!  A week has 7 days!  What day of this week is it?");
    var dayEntered = Console.ReadLine();
    int dayInt;
    bool success = int.TryParse(dayEntered, dayInt);
    if(!success || dayInt < (int)EDay.Monday || dayInt > (int)EDay.Sunday)
    {
        //either throw a new exception to go into your catch block or just have logic here.
    }
    EDay pickDay = (EDay)dayInt;
    Console.WriteLine("The day you picked was {0}", pickDay - 1);
    Console.ReadLine();
}
catch (Exception)
{
    Console.WriteLine("Please enter an actual numerical day of the week.");
    Console.ReadLine();
}

如何捕获与我的枚举参数不匹配的输入

3 个答案: