Re: Deallocating linked lists of linked lists

[cis.ohio-state.edu!zaphod.mps.ohio-state.edu!caen!msuinfo!netnews.upenn.e du!prijat!guinness.cs.uofs.edu!beidler@ucbvax.Berkeley.EDU (Jack Beidler)]

In article <1993Apr20.044555.154198@zeus.calpoly.edu>, jplee@cymbal.calpoly.edu
 (JASON LEE) writes:
|> Here's a good question...
|> 
|> I wrote a program that simulates a graph, and thus I need to have a linked
|> list, one of whose components is a linked list, showing on which vertices
|> that particular vertex is incident upon.
|> 
|> Well, enough of the nitty gritty.  Here is the question.  If I have a
|> variable that is a record, and one of the fields of the record is the head
|> pointer to another linked list, will it be sufficient to just deallocate the
|> one variable, or do I have to go inside and deallocate everthing?  Here are
|> my type declarations:
|> 
|> 
|>  << stuff deleted >>

Depends upon what you are using to perform the deallocation.  Typically,
a deallocation process deallocates one record during one call to the
process.  However, sometime when components are packaged, they might
contain a dealloation process that "knows" the structure of your data,
hence it can use that structure to properly deallocate the records in
the structure.  Most low level deallocation processes don't "know"
the structure you are using, hence they cannot use information in the
record passed to the deallocator to deallocate a structure.  

By your posting it sounds to me as if you are using a low level
deallocator with a structure you are encapsulating, in which case,
at best the deallocator will return the space to the heap of
available space -- at worst, the deallocator might just throw it
away and not recycle it, i.e., you have to write a low level
set of routines to maintain and recycle space!!

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