Simple Student Problem Ada83

Simple Student Problem Ada83

[mrbunny]

I have started a computer programming course at Thames Valley
University in Slough, UK. where we are using Ada 83  for an
introduction to programming.

I have a simple problem but cannot find an answer in my course notes
or text books! How do I delete a record from an array? The set up for
the array is as follows;

TYPE item_rec IS
              RE CORD
                    	ref_num   	: refnum_type;
                      	descrip   	: descrip_type;
                      	value      	: integer;          	
                      	hirer        	: name_type;        	
              END RECORD;

TYPE item_array IS ARRAY(integer RANGE <> ) OF item rec;

-- declare data variable to hold stock data

max_size : CONSTANT integer := 20;         	
stock : item_array(l..max_size);
num_items : integer; 


-- Instantiation of array_file to hold stock items data

PACKAGE item_file IS NEW array_file(item_rec, item_array,
"stock.dat");

Can anyone advise of a simple solution?

Thanks for your help.

Mark.

Re: Simple Student Problem Ada83

[Nick Roberts]

Bob Klungle <grbg@junque.com> wrote in article
<01bc4cd3$f8a7fae0$9bfd1fcc@p5120.bda>...
> Several possibilities come to mind without thinking much. No elegance,
just
> hack.
[hackish solution]

Alternatively,

(a) suppose the array is called A

(b) suppose the number of valid components in A at any particular time is
in n

(c) suppose the component of A to be deleted is number i

a slightly less hackish solution might go along these lines:

(1) check that i is not greater than n (what should we do if it is?)

(2) copy the components from A(i+1..n) into A(i..n-1)

(3) decrement n

I will leave coding this into Ada as an exercise, since this is supposed to
be an exercise for you! Answer the question posed at the end of (1) - it is
an important question.

Also, answer the following question. The copy in (2) will be implemented by
Ada as a loop, copying the machine elements, let's say bytes, of the array
slice specified. This loop will have two 'byte pointers' addressing the
byte to be copied from and the byte to be copied to. There are two possible
schemes: (1) both pointers are set at their respective last bytes to be
copied, and both are decremented; (2) both pointers are set to their
respective first bytes and both incremented. Which scheme - (1) or (2) -
will be used in this particular example, and why?

Nick.

Re: Simple Student Problem Ada83

[Robert Dewar]

iNick Roberts said

<<I will leave coding this into Ada as an exercise, since this is supposed to
be an exercise for you! Answer the question posed at the end of (1) - it is
an important question.>>

Nope, the excercise was to *figure out how* to do the coding. When you
give someone this much of a roadmap, you have entirely undrmined an
assignment. The coding is entirely secondary.