Inno Setup - Convert array of string to Unicode and back to ANSI

Solution 1:

To convert a file encoded in a specific Ansi encoding to Unicode string (UTF-16 LE), use MultiByteToWideChar function:

function MultiByteToWideChar(
  CodePage: UINT; dwFlags: DWORD; const lpMultiByteStr: AnsiString;
    cchMultiByte: Integer; lpWideCharStr: string; cchWideChar: Integer): Integer;
  external '[email protected] stdcall';  

function LoadStringFromFileInCP(
  FileName: string; var S: string; CP: Integer): Boolean;
var
  Ansi: AnsiString;
  Len: Integer;
begin
  Result := LoadStringFromFile(FileName, Ansi);
  if Result then
  begin
    Len := MultiByteToWideChar(CP, 0, Ansi, Length(Ansi), S, 0);
    SetLength(S, Len);
    MultiByteToWideChar(CP, 0, Ansi, Length(Ansi), S, Len);
  end;
end;

function LoadStringsFromFileInCP(
  FileName: string; Strings: TStrings; CP: Integer): Boolean;
var
  S: string;
begin
  Result := LoadStringFromFileInCP(FileName, S, CP);
  if Result then Strings.Text := S;
end;

(Note that I'm using TStrings to store strings/lines collection instead of TArrayOfString, as TStrings is easier to work with)

To convert Unicode string back to Ansi, use WideCharToMultiByte function:

function WideCharToMultiByte(CodePage: UINT; dwFlags: DWORD;
  lpWideCharStr: string; cchWideChar: Integer; lpMultiByteStr: AnsiString;
  cchMultiByte: Integer; lpDefaultCharFake: Integer;
  lpUsedDefaultCharFake: Integer): Integer;
  external '[email protected] stdcall';

function SaveStringToFileInCP(FileName: string; S: string; CP: Integer): Boolean;
var
  Ansi: AnsiString;
  Len: Integer;
begin
  Len := WideCharToMultiByte(CP, 0, S, Length(S), Ansi, 0, 0, 0);
  SetLength(Ansi, Len);
  WideCharToMultiByte(CP, 0, S, Length(S), Ansi, Len, 0, 0);
  Result := SaveStringToFile(FileName, Ansi, False);
end;

function SaveStringsToFileInCP(
  FileName: string; Strings: TStrings; CP: Integer): Boolean;
begin
  Result := SaveStringToFileInCP(FileName, Strings.Text, CP);
end;

Use the functions like:

const
  CP_EUC_KOREAN = 51949;

var
  I: Integer;
  Strings: TStrings;
begin
  Strings := TStringList.Create;
  if LoadStringsFromFileInCP('korean.txt', Strings, CP_EUC_KOREAN) then
  begin
    for I := 0 to Strings.Count - 1 do
    begin
      MsgBox(Strings[I], mbInformation, MB_OK);
    end;
  end;

  SaveStringsToFileInCP('korean_out.txt', Strings, CP_EUC_KOREAN);
end;

Works correctly on my English-only system: