Pass a multidimensional array as a parameter in De

问题:

I'd like to pass a multi-dimensional array to a constructor like so:

constructor TMyClass.Create(MyParameter: array of array of Integer);
begin
  LocalField := MyParameter;
end;

Where LocalField is an array of array of Integer.

However the above code won't compile ('Identifier expected but ARRAY found'). Could somebody explain to me why this is wrong? I tried reading up on open, static and dynamic arrays but have yet to find something that works. Is there a way to fix it without changing the type of LocalField?

回答1:

Make a specific type for localfield, then set that as the type of MyParameter, something along the lines of:

type
  TTheArray = array[1..5] of array[1..10] of Integer;

var
  LocalField: TTheArray;

constructor TMyClass.Create(MyParameter: TTheArray);
...

(Note: not verified in a compiler, minor errors may be present)

Note that most often in pascal-like syntax a multidimensional array is more properly declared as

type
  TTheArray = array[1..5, 1..10] of Integer;

Unless, of course, you have some good reason for doing it the other way.

回答2:

I don't have Delphi at hands, but I think this should work:

type
  TIntArray = array of Integer;

...

constructor TMyClass.Create (MyParameter : array of TIntArray);
begin
...
end;

回答3:

If a type is used before as suggested in the answer, please note that you are passing it as a reference, see:

https://blog.spreendigital.de/2016/08/01/pass-a-multidimensional-array-as-a-parameter-with-a-hidden-caveat/

回答4:

I prefer this

procedure MakeMat(var c: TMatrix; nr, nc: integer; a: array of double);
var
  i, j: integer;
begin
  SetLength(c, nr, nc);
  for i := 0 to nr-1 do
    for j := 0 to nc-1 do
      c[i,j] := a[i*nc + j];
end;


MakeMat(ya, 5, 11,
       [1.53,1.38,1.29,1.18,1.06,1.00,1.00,1.06,1.12,1.16,1.18,
        0.57,0.52,0.48,0.44,0.40,0.39,0.39,0.40,0.42,0.43,0.44,
        0.27,0.25,0.23,0.21,0.19,0.18,0.18,0.19,0.20,0.21,0.21,
        0.22,0.20,0.19,0.17,0.15,0.14,0.14,0.15,0.16,0.17,0.17,
        0.20,0.18,0.16,0.15,0.14,0.13,0.13,0.14,0.14,0.15,0.15]);