CString s( "文字列" );
char *c;
int siz;
::SendMessage( hWnd, WM_SETTEXT, 0, (LPARAM)s );
siz = ::SendMessage( hWnd, WM_GETTEXTLENGTH, 0, 0 );
c = new char[ siz + 1 ];
::SendMessage( hWnd, WM_GETTEXT, siz + 1, (LPARAM)c );