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From: Reinert Korsnes on 20 Jun 2008 09:19
I try to learn to use Ada.Containers.
Assume the following code:

package X_t is new Vectors(Positive,Item_t);
use X_t;
X : Vector;

-- I want something more beautiful than this loop:

for k in 1 .. Positive(X.Length) loop
do_something(X.Element(k));
end loop;

Could anybody suggest improvements for the three
last lines in the code?

reinert

From: Pascal Obry on 20 Jun 2008 10:49
Reinert Korsnes a �crit :
> Could anybody suggest improvements for the three
> last lines in the code?

A solution using the Iterate routine:

procedure Do_Something (P : X_t.Cursor) is
E : constant Item_T := Element (P);
begin
...
end Do_Something;

X.Iterate (Do_Something'Access);

Another solution would be to loop using a cursor, something like:

P : X_t.Cursor := X.First;

while Has_Element (P) loop
Do_Something (P);
Next (P);
-- With this loop it is possible to exit before the end
-- exit when <some_condition>;
end loop;

Both example have not been compiled, so could have some syntax error but
you get the idea.

Pascal.

--

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From: Jeffrey R. Carter on 20 Jun 2008 15:21
Reinert Korsnes wrote:
>
> for k in 1 .. Positive(X.Length) loop
> do_something(X.Element(k));
> end loop;
>
> Could anybody suggest improvements for the three
> last lines in the code?

for K in 1 .. X.Last_Index loop
Do_Something (X.Element (K) );
end loop;

Since the correct name for this package is Unbounded_Arrays, it makes sense to
iterate over it in a manner to iterating over an array.

--
Jeff Carter
"C's solution to this [variable-sized array parameters] has real
problems, and people who are complaining about safety definitely
have a point."
Dennis Ritchie
25
From: Reinert Korsnes on 20 Jun 2008 15:48
Jeffrey R. Carter wrote:

> Reinert Korsnes wrote:
>>
>> for k in 1 .. Positive(X.Length) loop
>> do_something(X.Element(k));
>> end loop;
>>
>> Could anybody suggest improvements for the three
>> last lines in the code?
>
> for K in 1 .. X.Last_Index loop
> Do_Something (X.Element (K) );
> end loop;
>
> Since the correct name for this package is Unbounded_Arrays, it makes
> sense to iterate over it in a manner to iterating over an array.
>

Maybe better:

for K in X.First_Index .. X.Last_Index loop
Do_Something (X.Element (K) );
end loop;

?

Just in case someone in the future change the vector indexing type.
The first element need not correspond to index = 1.

reinert


From: Matthew Heaney on 23 Jun 2008 13:08
On Jun 20, 9:19 am, Reinert Korsnes <a...(a)b.no> wrote:
>    for k in 1 .. Positive(X.Length) loop
>        do_something(X.Element(k));
>    end loop;
>
> Could anybody suggest improvements for the three
> last lines in the code?

for K in X.First_Index .. X.Last_Index loop
Do_Something (X.Element (K));
end loop;
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