How to set the default file pattern for the igrep-find command in c++-mode

[Avi]

Hi,
I'm looking for a way to set the default file pattern for the igrep-
find command.
In c-mode, the following line defines a multiple file pattern in one
string:
(put 'igrep-files-default 'c-mode (lambda () "*.[ch]"))
This captures both *.h and *.c files
I am looking for something similar for the c++-mode.
I have tried the following line:
(put 'igrep-files-default 'c++-mode (lambda () "*.[cpp|h]"))
but this is parsed as *.c *.p *.h (rather than *.cpp *.h)
Another option is to customize the read-multiple-files variable to
true. This allows to insert multiple patterns but requires interaction
(every pattern needs to be specified and confirmed by clicking on the
"Enter" key.

Thanks,
Avner