How to make silently truncate for char type

I upgraded postgresql 7.1 to 7.2 and found that many
sql cannot execute because version 7.2 does not
silently truncate the string for char(n) type during
insert a new row.
e.g. insert t (field1) value ('abcdef');
     where field1 is char(5) but I insert the string
has 6 characters.

How can I solve the problem except downgrade the
Postgresql?

Looking forward to your reply!!!

=====
Yours sincerely,
    Leung Chun Man, Terence

    Mobile: (852) 9273 9176
    Homepage:  http://tcmleung.uhome.net ,
    http://www.dynamicdrive.com/dynamicindex4/filter/index.htm

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