Hi Bo! :-)

 BS>>> for(tmpStruct=firstStruct; tmpStruct; tmpStruct=tmpStruct->next)
 BS>>> {
 BS>>>    free(tmpStruct);      
 BS>>> }
 RS>>  Well, you don't want to try to access tmpStruct after 
 RS>> you have free'd it.  I would do something more like 
 RS>> this...
 BS> So you set it to NULL after freeing it?
The problem with your above code is that you do free(tmpStruct) and then
access tmpStruct->next, but you don't know what free() does, it could
for example overwrite the contents of tmpStruct->next. Usually it
doesn't, but you cannot be certain.

You could even want to have a free() that zeroes memory or writes some
pattern to it to catch "use after free" bugs semi-automatically.
The Linux kernel, for example, has stuff like this in its linked list code.
Deleting a list item writes special "poison" values into its prev
and next pointers, so that the rest of the code can find out when it is
being passed a list element that was supposed to be deleted already.

Ciao
Pascal

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