Ada- raised Constraint_error : bad input for 'Value:

Question

我正在尝试使用 Integer'Value 将字符串转换为整数。这对于通过文件的第一个循环工作正常，但之后我得到一个错误的 'value (raised Constraint_Error) 输入。我希望有人能告诉我我的方法的错误，这样我就可以转换字符串到每个循环的整数。

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;

Answer 1

问题是您在创建数组后弄乱了数组的长度。不要那样做。

而不是

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

声明时直接将Stripped_Line初始化为正确的大小即可。

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

我假设您的 "Strip" 函数在这里正常工作..

Ada- raised Constraint_error : bad input for 'Value:

Ada- raised Constraint_error : bad input for 'Value:

arrays

string

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