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multi-dimensional open array parameter?

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taazz:
you do something along the lines of

--- Code: ---type
type
  T2DIntArray = array of array of Integer;

procedure CallOnArray(var anArray:T2DIntArray);
begin

end;

procedure SetLength2D(var anArray:T2DIntArray; Dim1,Dim2:Integer);
var
  vCntr : integer;
begin
  SetLength(anArray,Dim1);
  for vCntr := 0 to Dim1-1 do begin
    SetLength(anArray[vCntr],Dim2);
  end;
end;

procedure Test;
var
  ar2 : T2dIntArray;
begin
  SetLength2D(ar2,2,3);
  callOnArray(ar2);
end;

--- End code ---

Leledumbo:
I suggest using container classes such as list instead of arrays for this. However, I don't think there's something built-in for this. So I end up writing this:

--- Code: ---{$mode objfpc}{$H+}

uses
  fgl;

type
 
  TIntegerList = class(specialize TFPGList<Integer>)
  private
    function GetIt(Index: Integer): Integer;
    procedure PutIT(Index: Integer; const Item: Integer);
  public
    property Items[i: Integer]: Integer read GetIt write PutIt; default;
  end;
 
  TIntegerMatrix = class(specialize TFPGObjectList<TIntegerList>)
  private
    function GetIt(Index: Integer): TIntegerList;
  public
    constructor Create;
    property Items[i: Integer]: TIntegerList read GetIt; default;
  end;

{ TIntegerList }

function TIntegerList.GetIt(Index: Integer): Integer;
begin
  if Index >= Count then Result := 0 else Result := Get(Index);
end;

procedure TIntegerList.PutIt(Index: Integer; const Item: Integer);
begin
  if Index >= Count then Count := Index + 1;
  Put(Index,Item);
end;

{ TIntegerMatrix }

constructor TIntegerMatrix.Create;
begin
  inherited Create(true);
end;

function TIntegerMatrix.GetIt(Index: Integer): TIntegerList;
var
  OldCount,i: Integer;
begin
  if Index >= Count then begin
    OldCount := Count;
    Count := Index + 1;
    for i := OldCount to Count - 1 do begin
      Put(i,TIntegerList.Create);
    end;
  end;
  Result := Get(Index);
end;

procedure ManipulateIntegerMatrix(m: TIntegerMatrix);
var
  i,j: Integer;
begin
  for i := 0 to m.Count - 1 do
    for j := 0 to m[i].Count - 1 do
      m[i][j] := -m[i][j];
end;

var
  a: TIntegerMatrix;
  i,j: Integer;
begin
  a := TIntegerMatrix.Create;

  a[0][0] := 1; a[0][1] := 2; a[0][2] := 3;
  a[1][0] := 4; a[1][1] := 5; a[1][2] := 6;
  a[2][0] := 7; a[2][1] := 8; a[2][2] := 9;

  WriteLn('Before:');
  for i := 0 to a.Count - 1 do begin
    for j := 0 to a[i].Count - 1 do
      Write(a[i][j]:3);
    WriteLn;
  end;

  ManipulateIntegerMatrix(a);
 
  WriteLn('After:');
  for i := 0 to a.Count - 1 do begin
    for j := 0 to a[i].Count - 1 do
      Write(a[i][j]:3);
    WriteLn;
  end;

  a.Free;
end.

--- End code ---
Note that my convention is no error shall be generated for accessing index outside existing ones. Instead, 0 shall be returned for inner index, while new TIntegerList instance will be returned for outer index. It's up to you whether to follow or change this.

photor:
Thanks for all the warm replies. But it is a pity that free pascal doesn't support multi-dimensional open array parameters. To me, extending the function of one-dimensional open array parameters to the multi-dimensional case is not a big challenge to the free pascal developers.

User137:
Was there something wrong with taazz code? I can give another example

--- Code: ---type
  TArr = array of array of integer;
...
procedure Test(arr: TArr);
begin
  arr[high(arr), high(arr[0])]:=1;
end;

procedure TForm1.FormCreate(Sender: TObject);
var arr: TArr;
begin
  setlength(arr, 10, 20); // 10x20 matrix
  arr[9, 19]:=0;
  Test(arr);
  caption:=inttostr(arr[9, 19]); // Sets caption 1
end;
--- End code ---
In nowhere did i tell Test() function that the matrix size was 10x20, but it could still modify the last value.

Leledumbo:

--- Quote from: photor on May 31, 2014, 12:17:50 pm ---Thanks for all the warm replies. But it is a pity that free pascal doesn't support multi-dimensional open array parameters. To me, extending the function of one-dimensional open array parameters to the multi-dimensional case is not a big challenge to the free pascal developers.

--- End quote ---
If you think so, then implement. Welcome to open source world.

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