比较输入的字符串和枚举类型 [英] Compare a string input to an Enumerated type

问题描述

我正在寻找一个字符串与和枚举的比较。我已经写了我要尝试的示例代码。由于String和枚举类型不同，因此如何在Ada中正确执行此操作？

I am looking to do a comparison of a string to and enumeration. I have written a sample code of what I am attempting. Since a String and and Enumerated type are different, how do I go about doing this properly in Ada?

WITH Ada.Text_IO; USE Ada.Text_IO;

PROCEDURE ColorTest IS

   TYPE StopLightColor IS (red, yellow, green);

   response : String (1 .. 10);
   N : Integer;

BEGIN
   Put("What color do you see on the stoplight? ");
   Get_Line (response, N);
   IF response IN StopLightColor THEN
      Put_Line ("The stoplight is " & response(1..n));
   END IF;

END ColorTest;

推荐答案

首先实例化 Enumeration_IO StopLightColor ：

package Color_IO is new Ada.Text_IO.Enumeration_IO(StopLightColor);

然后您可以执行以下任一操作：

Then you can do either of the following:

• 使用 Color_IO.Get 读取值，捕获任何 Data_Error 出现，如此处所示，用于 Enumeration_IO 的类似实例。

• Use Color_IO.Get to read the value, catching any Data_Error that arises, as shown here for a similar instance of Enumeration_IO.

使用 Color_IO.Put 获得 String 与响应进行比较。

另外，对于枚举类型的标识符， Stoplight_Color 可能是更一致的样式。

As an aside, Stoplight_Color might be a more consistent style for the enumerated type's identifier.

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