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From: aaron@rruxh.UUCP (Akman)
Newsgroups: comp.lang.c++
Subject: comp.lang.c++
Message-ID: <AARON.90Jun8092635@rruxh.rruxh.UUCP>
Date: 8 Jun 90 13:26:35 GMT
Sender: news@bellcore.bellcore.com
Distribution: comp
Organization: Bellcore
Lines: 52


A few C++ Questions:

In Stroustrup pp. 163-166:

1. Is it still true that setting 'this' and zeroing it tell the
compiler not to use the free store?  I understand it this way (am I
correct?):  The compiler checks the constructor for 'this =
something' and if it finds that it won't bother getting storage for
'this' on entry to the constructor; otherwise the constructor is
called with a 'this' pointer that has already been given some storage.

2. Can someone explain the infinite loop in 5.5.6?  I'm a little confused.

3. In 5.5.8, we're familiar with this variable-sized object trick
from the good 'ol days of C, but it's a little confusing to see:

	class char_stack {
		// whatever...
		char s[1];
	   public:
		char_stack(int sz);
		// and so on...
	};

because we (I) think of structure members as being contiguous data
in memory.  I realize that char_stack is not data, but a function
member.  My question is:  What is really happening internally here?
I'm guessing that all the data parts are collected in contiguous
memory, no per-object space is allocated for any of the function
members, but some housekeeping type pointer helps an object find its
class functions in a shared place.  So, really, there is nothing
that comes after 'char s[1]' in that example?

4. Do I have this right?

	char_stack s1(100);	
	char_stack s2 = s1; // from p. 157

	s2 = s1;

The 1st one says:  allocate a char_stack and call the constructor
that expects an int (or whatever).  The second says, allocate a
char_stack and call the X(X&) constructor.  The second case is NOT
an assignment.  The 3rd case says call 'operator=' for s2 with s1 as
its argument.  Is the default 'operator=' bitwise copy, or is it
undefined?  I understand why these assignments are dangerous in the
example shown.
--

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Aaron Akman, 201-699-8019, bellcore!rruxh!aaron, RRC 4D-728