Re: determining input data type

[anon@anon.org (anon)]

--
-- Without knowing what format your data is in it is kind of 
-- hard to decide what way is the best. Some ways are easy 
-- while others are more complex
--
-- But if the data is a packed buffer string then you could use 
-- Ada.Characters.Handling.Is_Digit.
--
-- In this case the best was is to use a loop and search for all 
-- valid data where the search routine would find the integer 
-- value and no error occurs unless the data is float. Also in this 
-- example, only base 10 integers are valid.
--
with Ada.Text_IO ;
use Ada.Text_IO ;

with Ada.Integer_Text_IO ;
use Ada.Integer_Text_IO ;

with Ada.Characters.Handling ;
use  Ada.Characters.Handling ;

procedure b is

  Data_Error : exception ;

  function To_Integer ( Buffer : String ) return Integer is

    Index : Natural ;
    First : Natural ; -- first valid digit
    Last  : Natural ; -- Last valid digit

  begin -- To_Integer
    Index := Buffer'First ;
    while Index <= Buffer'Last and then 
          not is_digit ( Buffer ( Index ) ) loop 
      Index := Index + 1 ;
    end loop ;
    First := Index ; 

    while Index <= Buffer'Last and then
          is_digit ( Buffer ( Index ) ) loop 
      Index := Index + 1 ;
    end loop ;
    Last := Index - 1 ;

    --  check for decimal point aka the number is float

    if Index <= Buffer'Last and then
       Buffer ( Index ) = '.' then  
       raise Data_Error ;
    end if ;
  
    return Integer'Value ( Buffer ( First..Last ) ) ;

  exception
    when Data_Error =>
      Put_Line ( "Data was invalid -- need to check data source" ) ;
      Put_Line ( "Invalid Data element =>" & Buffer ( Index ) ) ;
      raise ;
  end To_Integer ;


  Data   : integer ;

begin -- b

  Data := To_Integer ( " =123;" ) ;

  Put ( "Data => " ) ;
  Put ( Data ) ;
  New_Line ;


  -- Data_Error is raised

  Data := To_Integer ( "asv456" ) ; 

  Put ( "Data => " ) ;
  Put ( Data ) ;
  New_Line ;

  -- Data_Error is raised

  Data := To_Integer ( " =789.;" ) ; 

  Put ( "Data => " ) ;
  Put ( Data ) ;
  New_Line ;

exception
  when Data_Error =>
      null ;
end b ;

In <d39e1918-0c74-40b5-860d-f8d93181afd2@p59g2000hsd.googlegroups.com>, jedivaughn <jedivaughn14@gmail.com> writes:
>Hi, How is the best way to determine the type of input. I have the
>input coming in through a string but if the contents of the string is
>an integer then I want to convert it to such. This seems like it
>should be very easy to do but I can't seem to find out how to do it
>any where.
>
>
>Thanks,
>
>John