hsr////////////////////////////////////////////////////////////
StringTowidechar함수를 사용해보세요

procedure TForm1.Button1Click(Sender: TObject);
var
    awc1 : array[0..5] of WideChar;
    awc2 : array[0..5] of WideChar;
    str : string;
begin
    str := '012345';
    StringTowidechar(str,@awc1,7);
    showmessage(string(awc1));

    StringTowidechar(string(awc1),@awc2,7);
    showmessage(string(awc2));
end;
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예제로는 아래 참조하시구요, 관련함수들도 도움말에 있습니다.
strPcopy나 strcopy등...
1번
procedure TForm1.Button1Click(Sender: TObject);
var
    s : String;
    p : Pwidechar;
    i : integer;
begin
    s := '12345';
    GetMem(P, 256);
    StringTowidechar(s,p,length(s)+1);
    //i := lstrlenW(p); //길이
    i := StrToint(string(p));
    showmessage(intToStr(i));
    showmessage(string(p));
end;

2번
procedure TForm1.Button1Click(Sender: TObject);
var
    s : String;
    p : Pwidechar;
    Buffer: array[0..256] of widechar;
    i : integer;
begin
    s := '12345';
    P := StringTowidechar(s,Buffer,length(s)+1);
    i := StrToint(string(p));
    showmessage(intToStr(i));
    showmessage(string(p));
    showmessage(string(Buffer));
end;