请教几个函数

Question

{ ----------------------------------------------------- }
{       Wide character support                          }
{ ----------------------------------------------------- }function WideCharToString(Source: PWideChar): string;
begin
  WideCharToStrVar(Source, Result);
end;function WideCharLenToString(Source: PWideChar; SourceLen: Integer): string;
begin
  WideCharLenToStrVar(Source, SourceLen, Result);
end;procedure WideCharToStrVar(Source: PWideChar; var Dest: string);
begin
  _LStrFromPWChar(Dest, Source);
end;procedure WideCharLenToStrVar(Source: PWideChar; SourceLen: Integer;
  var Dest: string);
begin
  _LStrFromPWCharLen(Dest, Source, SourceLen);
end;function StringToWideChar(const Source: string; Dest: PWideChar;
  DestSize: Integer): PWideChar;
begin
  Dest[WCharFromChar(Dest, DestSize - 1, PChar(Source), Length(Source))] := #0;
  Result := Dest;
end;