Category : Pascal Source Code
Archive   : VMMNGR.ZIP
Filename : EXDYNARR.PAS

program DynArrayExample;

uses
OpCrt,
OpRoot,
Vmmngr;

type
ExpRecord
= record
Name : string[25];
Age,
Class: word;
end;
var
ExpArray : DynArray;
RecBuffer : ExpRecord; {buffer to put and get data to and from ExpArray}
Key,
Status,
NbElem,
NumIncr : word;
S : DosIdStream;

procedure ShowStatus;
{-Display status of ExpArray}
begin
Writeln('ExpArray size is now : ', ExpArray.GetArraySize);
Writeln('ExpArray status is : ', ExpArray.GetStatus);
end;

procedure ShowContents(index : word);
{-Show contents of one element of ExpArray}
begin
ExpArray.GetElem(index, RecBuffer);
Writeln('Element #',index, ' Name is : ', RecBuffer.Name);
Writeln('Element #',index, ' Age is : ', RecBuffer.Age);
Writeln('Element #',index, ' Class is : ', RecBuffer.Class);
end;

begin
Write('Enter the maximum number of elements for the array : ');
ReadLn(NbElem);
Write('Enter the minimum increment when growing (number of elements) : ');
ReadLn(NumIncr);
ClrScr;
{Creates a dynamic array of ExpRecord}
if not ExpArray.Init(NbElem,
SizeOf(ExpRecord),
NumIncr) then begin
WriteLn('Failed to Create DynArray, Status = ', InitStatus);
Halt;
end;
Writeln('After initialization, the array size is 0...');
ShowStatus;

{Load RecBuffer}
Recbuffer.Name := 'Name0';
Recbuffer.Age := 0; {Not realistic but helps seeing how things work}
RecBuffer.Class := 0;

{Store RecBuffer in the dynamic array}
ExpArray.SetElem(0, RecBuffer);

{Size increase to the minimum increment}
Writeln('Setting the first element will increase the size to the minimum increment...');
Writeln('One element occupies ', ExpArray.GetElemSize, ' bytes');
ShowStatus;
ShowContents(0);

{Load another value at maximum index }
Recbuffer.Name := 'NameMax';
Recbuffer.Age := ExpArray.GetMaxIndex;
RecBuffer.Class := Recbuffer.Age;
ExpArray.SetElem(ExpArray.GetMaxIndex, RecBuffer);

{The size was increased to receive the last element}
Writeln('Setting the last element will likely require a size increase...');
ShowStatus;
ShowContents(ExpArray.GetMaxIndex);

{Elements non explicitly set are always 0}
Writeln('You can always assume that an element which has not been set is null...');
ShowContents(ExpArray.GetMaxIndex-1);
Writeln('Press any key');
While not KeyPressed do;
While Keypressed do Key :=ReadKeyWord;
ClrScr;

{Now storing the array in a stream, killing it and reloading it}
Writeln('Now storing the array...');
{Create a Stream, check for success}
if not S.Init('DYNARRAY.STM', SCreate) then begin
Writeln('Failed to Create Stream, Status = ', InitStatus);
Halt;
end;
{Register object hierarchy}
S.RegisterHier(DynArrayStream);
Status := S.GetStatus;
if Status <> 0 then begin
Writeln('Failed to Register objects, Status = ', Status);
Halt;
end;
S.Put(ExpArray);
Status := S.GetStatus;
if Status <> 0 then begin
WriteLn('Failed to Write ExpArray, Status = ', Status);
Halt;
end;

Writeln('Now killing ExpArray...');
ExpArray.Done;
S.done;

Writeln('Now reloading ExpArray...');
{Re-open the existing Stream}
if not S.Init('DYNARRAY.STM', SOpen) then begin
Writeln('Failed to Open Stream, Status = ', InitStatus);
Halt;
end;
{Re-register object hierarchy}
S.RegisterHier(DynArrayStream);
Status := S.GetStatus;
if Status <> 0 then begin
Writeln('Failed to register objects. Status = ', Status);
Halt;
end;
S.Get(ExpArray);
Status := S.GetStatus;
if Status <> 0 then begin
Writeln ('Failed to read ExpArray. Status = ', Status);
Halt;
end;
S.Done;
Writeln('Showing ExpArray first and last elements...');
ShowStatus;
ShowContents(ExpArray.GetMaxIndex);
ShowContents(0);
Writeln;
Writeln('Press any key');
While not KeyPressed do;
While Keypressed do Key :=ReadKeyWord;
ClrScr;

{Clearing the array just resets the size to 0 and free all data on the heap}
{However the array is still active and any element could be set}
Writeln('Now clearing the array...');
ExpArray.Clear;
Writeln('ExpArray size is now ', ExpArray.GetArraySize, ' bytes');
Writeln('ExpArray still alive : any element can be set.');

Writeln('Now testing error checking...');
Writeln('Trying to get the second element of the cleared array...');
ExpArray.GetElem(2, RecBuffer);
if ExpArray.GetStatus <> 0 then
Writeln('Failed to retrieve element data');
Writeln;
Writeln('Now trying to setup a very big array (30000 elements)...');
ExpArray.Done;
ExpArray.Init(30000, SizeOf(ExpRecord), 100);
if InitStatus <> 0 then
WriteLn('Failed to Create DynArray, Status = ', InitStatus);

ExpArray.done;
end.