Path: utzoo!attcan!ncrcan!scocan!tom
From: tom@sco.COM (Tom Kelly)
Newsgroups: comp.std.c++
Subject: delete [] p
Message-ID: <1990Aug16.162718.14828@sco.COM>
Date: 16 Aug 90 20:27:18 GMT
Organization: SCO Canada, Inc. (formerly HCR Corporation)
Lines: 39

The recent discussion of delete [] in comp.lang.c++ got me to thinking
about some example C++ code I've seen.

For example, in Lippman, _C++ Primer_, p. 234:
(with int len; char *str)

String::String(char *s)
{
	len = strlen(s);
	str = new char[len + 1];
	strcpy(str, s);
}

String::~String()
{
	delete str;
}

The same code (essentially) appears in Dewhurst & Stark,
_Programming in C++_, p. 70.

It seems to me that the delete statement is incorrect, it
should be delete [].  According to E&S (ARM), section 5.3.4, p. 21:

"The effect of deleting an array with the plain delete syntax
is undefined".

The annotations note that there is a practical difference only for
classes that have destructors, and of course, "char" has no
destructor.  But the annotation further points out that it is
possible that during program evolution, a built-in type can be
replaced by a class with a destructor (using typedef) and so this
is a dangerous practice.

Comments?

Tom Kelly  (416) 922-1937
SCO Canada, Inc. (formerly HCR) 130 Bloor St. W., Toronto, Ontario, Canada
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