Ada-提出了Constraint_error：“值： [英] Ada- raised Constraint_error : bad input for 'Value:

问题描述

我正在尝试使用Integer’Value将字符串转换为Integer。这对于文件的第一个循环工作正常，但是之后我得到了一个错误的'value输入（提高了Constraint_Error。我希望有人可以向我展示我的方式的错误，以便可以将字符串转换为整数）。

 与Ada.Text_IO，Ada.Integer_Text_IO; 
 USE Ada.Text_IO，Ada.Integer_Text_IO; 
 
过程Isbntest是
 
功能Strip（The_String：String; The_Characters：String）
返回字符串IS 
保留：ARRAY（字符）OF布尔值：= （OTHERS => True）; 
结果：String（The_String'RANGE）; 
 Last：Natural：=结果'First-1; 
开始
 FOR I IN The_Characters'范围LOOP 
 Keep（The_Characters（I））：= False; 
 END LOOP; 
 FOR J IN The_String'RANGE LOOP 
 IF Keep（The_String（J））THEN 
 Last：= Last + 1; 
 Result（Last）：= The_String（J）; 
 END IF; 
 END LOOP; 
 RETURN Result（Result'Fi rst .. Last）; 
 END St​​rip； 
 
 
输入：File_Type：= Ada.Text_IO.Standard_Input; 
 
开始
 
而不是End_of_File（Input）LOOP 
 DECLARE 
 Line：String：= Ada.Text_IO.Get_Line（Input）; 
 StrippedLine：字符串：=行; 
 ascii_val：整数：= 0; 
 
开始
 StrippedLine：= Strip（Line，-）; 
 ascii_val：=整数值（StrippedLine）； 
 Put（ascii_val）; 
 Put_line（StrippedLine）; 
 END； 
 END LOOP； 
关闭（输入）； 
结束测试； 
  

解决方案

问题是您弄乱了长度创建数组之后。不要这样做。

而不是

 声明
行：字符串：= Ada.Text_IO.Get_Line（输入）; 
 StrippedLine：字符串：=行; 
开始
 StrippedLine：= Strip（Line，-）; 
  

只需在声明时将Stripped_Line初始化为正确的大小即可。

 声明
 Line：String：= Ada.Text_IO.Get_Line（Input）; 
 StrippedLine：字符串：= Strip（Line，-）; 
开始
  

我假设您的 Strip功能在这里正常工作。 p>

I'm trying to use Integer'Value to convert a string to an Integer. This works fine for the first loop through a file, but after that I get a bad input for 'value (raised Constraint_Error. I was hoping someone could show me the error of my ways, so that I can convert the string to an integer on each loop.

WITH Ada.Text_IO, Ada.Integer_Text_IO;
USE Ada.Text_IO, Ada.Integer_Text_IO;

PROCEDURE Isbntest IS

  FUNCTION Strip(The_String: String; The_Characters: String)
        RETURN String IS
     Keep: ARRAY (Character) OF Boolean := (OTHERS => True);
     Result: String(The_String'RANGE);
     Last: Natural := Result'First-1;
  BEGIN
     FOR I IN The_Characters'Range LOOP
        Keep(The_Characters(I)) := False;
     END LOOP;
     FOR J IN The_String'RANGE LOOP
        IF Keep(The_String(J)) THEN
           Last := Last+1;
           Result(Last) := The_String(J);
        END IF;
     END LOOP;
     RETURN Result(Result'First .. Last);
  END Strip;


  Input: File_Type := Ada.Text_IO.Standard_Input;

BEGIN

   WHILE NOT End_of_File(Input) LOOP
     DECLARE 
     Line : String := Ada.Text_IO.Get_Line(Input);
     StrippedLine : String := line;
     ascii_val: Integer :=0;

  BEGIN
     StrippedLine := Strip(Line, "-");         
     ascii_val := integer'value(StrippedLine);
     Put(ascii_val);
     Put_line(StrippedLine);
  END;
   END LOOP;
   Close (Input);
end isbntest;

解决方案

The problem is that you're messing with the length of an array after you created it. Don't do that.

Instead of

  DECLARE 
     Line : String := Ada.Text_IO.Get_Line(Input);
     StrippedLine : String := line;
  BEGIN
     StrippedLine := Strip(Line, "-");   

Just initialise Stripped_Line directly to the correct size when you declare it.

  DECLARE 
     Line : String := Ada.Text_IO.Get_Line(Input);
     StrippedLine : String := Strip(Line, "-"); 
  BEGIN

I'm assuming your "Strip" function works correctly here..

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