XE6 ShortString与String相互转换

program Test;
{$APPTYPE CONSOLE}
uses
  System, System.SysUtils;
 
const
  Value: array[0..5] of Byte = (5, 72, 101, 76, 76, 111);  { Old ShortString representation of ‘Hello‘ }
 
type
  EShortStringConvertError = class(Exception)
  end;
 
function ShortStringToString(Value: array of Byte): String;
var
  B: TBytes;
  L: Byte;
begin
  Result := ‘‘;
  L := Value[0];
  SetLength(B, L);
  Move(Value[1], B[0], L);
  Result := TEncoding.Ansi.GetString(B);
end;
 
procedure StringToShortString(const S: String; var RetVal);
var
  L: Integer;
  I: Byte;
  C: Char;
  P: PByte;
  B: TBytes;
begin
  L := Length(S);
  if L > 255 then
    raise EShortStringConvertError.Create(‘Strings longer than 255 characters cannot be converted‘);
  SetLength(B, L);
  P := @RetVal;
  P^ := L;
  Inc(P);
  B := TEncoding.Ansi.GetBytes(S);
  Move(B[0], P^, L); 
end;
 
procedure DoTest;
var
  S: String;
  OldS: array[0..17] of Byte;  // Replacing string[17]
begin
  S := ShortStringToString(Value);
  WriteLn(‘#1 S=‘, S);
  S := ‘Excellence‘;
  StringToShortString(S, OldS);
  S := ‘‘;
  S := ShortStringToString(OldS);
  WriteLn(‘#2 S=‘, S);
end;
 
begin
  try
    DoTest;
  except
    on E: Exception do
      begin
        WriteLn(‘FAIL - Unexpected Exception‘);
        WriteLn(‘  ClassName=‘, E.ClassName);
        WriteLn(‘    Message=‘, E.Message);
      end;
  end;
end.