Availability:C-language interface function
bool PL_get_pointer(term_t 
+t, void **ptr)Together with PL_put_pointer() 
and PL_unify_pointer(), 
these functions allow representing a C pointer as a Prolog integer. The 
integer value is derived from the pointer, but not equivalent. The 
translation aims at producing smaller integers that fit more often in 
the tagged integer range. Representing C pointers as integers 
is unsafe. The blob API described in section 
12.4.10 provides a safe way for handling foreign resources that 
cooperates with Prolog garbage collection.