44 lines
1.3 KiB
Ada
44 lines
1.3 KiB
Ada
with Ada.Text_IO;
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procedure Middle_Three_Digits is
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Impossible: exception;
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function Middle_String(I: Integer; Middle_Size: Positive) return String is
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S: constant String := Integer'Image(I);
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First: Natural := S'First;
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Full_Size, Border: Natural;
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begin
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while S(First) not in '0' .. '9' loop -- skip leading blanks and minus
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First := First + 1;
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end loop;
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Full_Size := S'Last-First+1;
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if (Full_Size < Middle_Size) or (Full_Size mod 2 = 0) then
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raise Impossible;
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else
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Border := (Full_Size - Middle_Size)/2;
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return S(First+Border .. First+Border+Middle_Size-1);
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end if;
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end Middle_String;
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Inputs: array(Positive range <>) of Integer :=
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(123, 12345, 1234567, 987654321, 10001, -10001, -123, -100, 100, -12345,
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1, 2, -1, -10, 2002, -2002, 0);
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Error_Message: constant String := "number of digits must be >= 3 and odd";
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package IIO is new Ada.Text_IO.Integer_IO(Integer);
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begin
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for I in Inputs'Range loop
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IIO.Put(Inputs(I), Width => 9);
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Ada.Text_IO.Put(": ");
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begin
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Ada.Text_IO.Put(Middle_String(Inputs(I), 3));
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exception
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when Impossible => Ada.Text_IO.Put("****" & Error_Message & "****");
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end;
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Ada.Text_IO.New_Line;
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end loop;
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end Middle_Three_Digits;
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