incompatible types pwidechar and string ShellExecute

Question

I try to compress files using winrar command line, But when I add a variable in the command line I get these error Incompatible types 'PWideChar' and 'string' !

I convert the sdate variable to WideChar but it's not work !!

How I can fix it !

procedure TForm1.Button1Click(Sender: TObject);
var
mydate : TDateTime;
sdate : string;
begin
mydate:= Now-7;
sdate := FormatDateTime('YYYY/mm/dd',mydate);
  ShellExecute(0, 'open', PChar('C:\Program Files\WinRAR\WinRar.exe'),
    'a -r -ta'+ PChar(sdate) +' D:\xlsFiles.rar D:\*.xls*', nil, SW_SHOW);
end;

Answer 1

The text arguments of ShellExecute are of type PChar. But you supply a string for argument number 4.

The error message is very clear. You know by inspecting the declaration of ShellExecute that the problematic argument is of type PChar (an alias to PWideChar). And the error message tells you that you are passing a string.

Instead of

'a -r -ta'+ PChar(sdate) +' D:\xlsFiles.rar D:\*.xls*'

pass

PChar('a -r -ta'+ sdate +' D:\xlsFiles.rar D:\*.xls*')