grep -- option?

Does anyone know what the double dashes in the following grep line mean?

grep -c -- "->"

The intent of the line is to have a long listing of a directory piped to it, and for it to count off the symbolic links based on the "->" characters. I'm not sure why the scripter decided to search for the links in this manner. Anyway, I found it interesting, but can't seem to find any sort of documentation on the double dash. Am I missing something?

I'd like to know if there is any documentation on this and where.

Thanks!

Good post !

From

http://www.shelldorado.com/goodcoding/cmdargs.html

the following explanation on the use of --

If you for example had a file named "-f", it could not be removed using
the command "rm -f", because "-f" is a valid command line option. Instead you
can use "rm -- -f". The double dash "--" means "end of command line flags", and
the following "-f" is then interpreted as a file name.

Vino