Re: basic questions on using Ada arrays

[Jacob Sparre Andersen <sparre@nbi.dk>]

Nasser M. Abbasi wrote:

> I am really rusty with Ada. Wanted to find if I apply a function to an
> array in one call without having to loop calling the function for each
> entry in the array?

Only if the function/operation is declared for the array type.

The operator "and" is automatically declared for arrays of Booleans.

> Suppose I have an array of values, and I want to take the sin() of
> each value in the array?

The function "Sin" is not declared automatically for arrays of Floats.
You will have to declare it yourself:

   function Sin (Item : in The_Array_Type) return The_Array_Type is
   begin
      return Result : The_Array_Type do
         for I in Item'Range loop
            Result (I) := Sin (Item (I));
         end loop;
      end return;
   end Sin;      

> But I wanted to make each entry in the array to have some value
> depending on the index value.

You have to use a loop to do that (you may of course hide the loop in a
function).

> The bigger question really, is if one map functions on array in Ada,
> or do operations on array in one call, say like multiply a constant by
> array, without using loops all the time. loops are so out of fashion
> these days :)

There are generally no predefined mathematical operations on arrays of
scalars in Ada.  You could propose it to the ARG.  They might even
accept it.

> Something like this in Fortran
>
> ----------------------
> program main
>    integer :: x(10)=1 ;
>    x = 5 * x;
> end program
> -----------------------
>
> compiles, runs ok, but The Ada code
>
> ----------------------
> procedure test3  is
>    x   : array(1..10) of integer :=(others=>1);
> begin
>    x:= 5 * x;
> end test3;
> ---------------

... should be:

   procedure Test_3 is
      type Demo_Array is array (1 .. 10) of Integer;

      function "*" (Left : Integer; Right : Demo_Array)
        return Demo_Array is
      begin
         return Result : Demo_Array do
            for I in Right'Range loop
               Result (I) := Left * Right (I);
            end loop;
         end return;
      end "*";

      X : Demo_Array := (others => 1);
   begin
      X := 5 * X;
   end Test_3;

Jacob
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