Hi Kevan,
huge : Integer := 128_000_000;
Here the size of the array is predefined with a constant "huge".
No. "huge" is a variable that is initialised to 128,000,000. The memory is allocated dynamicly and it is allocated from the heap (the main memory pool).
Perhaps this is a better example for what you want
with Ada.Text_IO; use Ada.Text_IO; with Ada.Unchecked_Deallocation;
procedure Foo is
package Integer_IO is new Ada.Text_IO.Integer_IO (Integer); use Integer_IO;
type vector is array (Integer range <>) of Float; type vector_ptr is access vector; procedure Free_Vector is new Ada.Unchecked_Deallocation (vector, vector_ptr);
num : Integer;
begin
get (num); -- read the size of the array from standard input
declare
xg_ptr : vector_ptr := new vector (0..num); xg : vector renames xg_ptr.all;
begin Put (xg'last); New_line; Free_Vector (xg_ptr); -- essential to avoid memory leaks end;
end Foo;
And another example,
with Ada.Text_IO; use Ada.Text_IO; with Ada.Unchecked_Deallocation;
procedure Foo is
package Integer_IO is new Ada.Text_IO.Integer_IO (Integer); use Integer_IO;
type vector is array (Integer range <>) of Float; type vector_ptr is access vector; procedure Free_Vector is new Ada.Unchecked_Deallocation (vector, vector_ptr);
min, max : Integer;
procedure bahbah (min,max : Integer) is xg_ptr : vector_ptr := new vector (min..max); -- min, max unknown at compile time xg : vector renames xg_ptr.all; begin
Put (xg'last); New_line; Free_Vector (xg_ptr); -- essential to avoid memory leaks
end bahbah;
begin
get (min); get (max);
bahbah (min,max);
end Foo;
Cheers, Leo
On 6 January 2017 at 04:39, Kevan Hashemi hashemi@brandeis.edu wrote:
Leo: Thank you for your code example.
for i in 10 .. 20 loop
-- create xg on the stack (okay but stack size is limited) -- xg exists only within this declare block declare xg : Array (0..i-1) of Float; begin Put (xg'last); New_line; end;end loop;
That's the dynamic allocation I'm looking for, except it's on the stack. I need to use the main memory for dynamic allocation.
huge : Integer := 128_000_000;xg_ptr : vector_ptr := new vector (0..huge); xg : vector renames xg_ptr.all;begin Put (xg'last); New_line; Free_Vector (xg_ptr); -- essential to avoid memory leaks end;
Here the size of the array is predefined with a constant "huge".
Bastiaan: Thanks for the link. In the linked code we have:
VA := new Vector (1 .. 10); VB := VA; -- points to the same location as VA
Here, the vector size is predefined with the constants 1 and 10.
Peter: Thank you for your FPC example, which does exactly what I need.
program A; type graph_type = array of real; var xg:graph_type; i:integer; begin for i:=100 to 200 do begin setlength(xg,i); xg := nil; end; end.
Somehow, I missed setlength when I looked into FPC, and when I asked the FPC group about dynamic arrays, they must have interpreted my question as "does FPC support exactly the same syntax as GPC". So it looks like I could switch to FPC with minimal work.
Yours, Kevan
-- Kevan Hashemi, Electrical Engineer Physics Department, Brandeis University http://alignment.hep.brandeis.edu/