# Replace ideographic fullstop with CJK package

A common method to replace the ideographic fullstop (。) with fullwidth fullstop (．) is to change the catcode:

\catcode\。 = \active
\let。=．


However, this method will break when using CJK package with pdfLaTeX since this package has already made 。 to be a macro. So how to achieve this effect with CJK?

PS: I use UTF8 encoding.

I have found a similar question but for GBK encoding (in Chinese). Here is the solution:

% For GBK
% Put it after \begin{document}
\let\oldaone^^a1
\def^^a1#1{\ifnum#1=^^a3\relax ^^a3^^ae\else \oldaone #1\fi}


I have modified it for UTF8:

% For UTF8
% Put it after \begin{document}
\makeatletter
\let\old@e@iii=^^e3
\def^^e3^^80#1{%
\ifnum#1=^^82\relax
^^ef^^bc^^8e%
\else
\old@e@iii ^^80#1%
\fi}
\makeatother


Things like ^^xx are actually how the characters are represented under certain encodings: ^^e3^^80^^82 is "。" and ^^ef^^bc^^8e` is "．" in UTF8.