RosettaCodeData/Task/Array-concatenation/Delphi/array-concatenation.delphi

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type
TReturnArray = array of integer; //you need to define a type to be able to return it
function ConcatArray(a1,a2:array of integer):TReturnArray;
var
i,r:integer;
begin
{ Low(array) is not necessarily 0 }
SetLength(result,High(a1)-Low(a1)+High(a2)-Low(a2)+2); //BAD idea to set a length you won't release, just to show the idea!
r:=0; //index on the result may be different to indexes on the sources
for i := Low(a1) to High(a1) do begin
result[r] := a1[i];
Inc(r);
end;
for i := Low(a2) to High(a2) do begin
result[r] := a2[i];
Inc(r);
end;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
a1,a2:array of integer;
r1:array of integer;
i:integer;
begin
SetLength(a1,4);
SetLength(a2,3);
for i := Low(a1) to High(a1) do
a1[i] := i;
for i := Low(a2) to High(a2) do
a2[i] := i;
TReturnArray(r1) := ConcatArray(a1,a2);
for i := Low(r1) to High(r1) do
showMessage(IntToStr(r1[i]));
Finalize(r1); //IMPORTANT!
ShowMessage(IntToStr(High(r1)));
end;