Newsgroups: comp.lang.c++
Path: utzoo!utgpu!news-server.csri.toronto.edu!torsqnt!geac!alias!rae
From: rae@alias.com (Reid Ellis)
Subject: constructors and initializers
Message-ID: <1991May8.155352.18313@alias.com>
Keywords: constructor, default, class, array, definition
Sender: news@alias.com (USENET News)
Organization: Alias Research, Inc. Toronto ON Canada
References: <1991May2.165955.28385@iitmax.iit.edu> <701@taumet.com>
Date: Wed, 8 May 91 15:53:52 GMT

A note about initializers in constructors.  Recently, the following
class was mentioned under the subject line "HELP: default constructor
for array of class":

	class Point {
		int x;
	public:
		Point() { x = 200; }
		Point(int xc = 100) { x = xc; }
	};

Not to belabor the point [pun intentional] but the constructors should
be written as:

	class Point {
		int x;
	public:
		Point() : x(200) {}
		Point(int xc = 100) : x(xc) {}
	};

i.e. use initializers rather than assignment in a constructor.  Why?
The following line of code won't work with the first version, but will
work with the second version:

	const Point kPoint(23);

I just thought I'd mention this since I see assignment in constructors
in several examples people post here [not just "Point" :-)].

If this is imperious and sounds like I'm pontificating, feel free to
send me mail saying so. :)
					Reid, a.k.a. "Mister nit pick"
--
Reid Ellis
rae@utcs.toronto.edu        ||               rae@alias.com
CDA0610@applelink.apple.com ||      +1 416 362 9181 [work]