Undeclared identifier TEncoding delphi7

Hi i want to use TEncoding开发者_高级运维 to convert Tbytes to utf7 but when i use TEncoding delphi gives following error.

Undeclared identifier: 'TEncoding'

i am using delphi 7.

what to do??

The SysUtils.TEncoding class is not available in D7. Use the Win32 API MultiByteToWideChar() and WideCharToMultiByte() functions instead, specifying CP_UTF7 as the codepage.

TEncoding was introduced in Delphi 2009. You should upgrade to a newer version of Delphi, such as XE.