[Boost-users] How to cast a boost::shared_ptr to void*

Hi all, My requirement is to cast an object of type shared_ptr as void*, so that I can send it to a callback function that accepts a void*.  I cannot change callback the function signature because it is part of an existing legacy code. In the existing code, I am sending a raw object pointer (instead of shared_ptr).  Now, if I want to pass a shared_ptr, it won't compile because I cannot cast the shared ptr to void*.  Can anyone suggest some workaround for this.  I tried searching the mailing lists and internet, but not much luck. regards, RV