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An array of an array of records question...

Hi

I have the following question..
Am I doing this right? The point is I want to make a twodimensional array, which is in fact an array of another array type. This is what I do:

type FoodRec = record
FoodID : Integer;
FoodDescr : String[50];
FoodPortion : String[50];
FoodKCal : SmallInt;
FoodFat : SmallInt;
FoodQuantity : SmallInt;
FoodRecNo : SmallInt;
end;

type
MealFoods = Array of FoodRec;

var TotArray : Array of MealFoods;

then I can give it 'room' with setlength(TotArray[4][10]), in which 10 the dimension is of the Mealfoods array (I think..)
Is this the right way to do this? Or is there a more simple or safer way..

Thanks..

Regards

TheNeil

Well it compiles but I'd suggest that you actually define the sizes of your arrays in your type definitions. In your definition the 10 refers to the number of records while the 4 refers to the number of MealFood's. I've never seen SetLength used like that but it compiles and delphi seems happy enough with it but I'd still actually define the dimensions when you crate your types(go on, someone tell me I'm talking rubbish)

The Neil

Vendi

I have used SetLength with dynamic arrays but typically I've done it as follows:

var TotArray: array of array of FoodRec;
..
..
SetLength(TotArray, I, J);
{gives I x J array)

or...

SetLength(TotArray, I); Now you have an array of length I (I rows) whose elements you can set to arrays of varying length. Like SetLength(TotArray[1],5);

Also, it's pretty nice to use High, Low & Length functions with the dynamic arrays.

lizzzard

ASKER

Hi,

Thanks for your comments..

The Neil, I feet the same way as you do, the type definition might get me into trouble. Vendi's solution is I think the one I'm gonna use..

Thanks again,

Lizzzard.

OpitzS

Why don't you use
var
totarray: array of array of MealFoods;

That is in my oppinion more readable.

Sven

dvaline

frankly,
If you find this solution helpful email me at dvaline @ yahoo.com. And let me at the points. LOL.

I would create these records as TObject descendants. Adding as a property to the first level of records a property which is descended off of TList. This way you can use the power of OO and you can do validation and such as a contained business object.

Example.
TMyFirstItem = class(TObject)
private
fIntItem: Integer;
fStrItem: String;
fSecondList: TMySecondList;
public
constructor Create;
// create the list object
destructor Destroy; override;
// free the list object
property StringItem: String read fStrItem write fStrItem;
property IntItem: Integer read fIntItem write fIntItem;
property SecondList: TMySecondList read fSecondList;
end;

TMyFirstList = Class(TList)
private
procedure SetItem(Index: Integer; Value: TMyFirstItem);
function GetItem(Index: Integer): TMyFirstItem;
public
function Add: TMyFirstItem;
procedure Delete(Index: Integer);
// make sure to free your objects
procedure Clear;
property Items[Index: Integer]: TMyFirstItem read GetItem write SetItem;
end;

// you would duplicate this kind of
// declaration for your second item
// and list.

niknoxe

Take a look at this

{$R-}

type
PFoodRec = ^FoodRec;
FoodRec = record ... end;
type
MealFoods = array [0..0] of PFoodRec;

begin
MealFoods = new (SizeOf (FoodRec)*WantedItems));

for i:= 1 to WnatedItems-1 do begin
with MealFoods [i]^ do begin
...
end;
end;

This is not OO, o.k. But it works. You can nest them, if you want. It this is not the thing you want, start building objects as described.

ASKER CERTIFIED SOLUTION

Vendi

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lizzzard

ASKER

OK,

Thanks Vendi.. Sorry, I should have asked you myself...

Regards,

Lizzzard