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From: ark@alice.UUCP (Andrew Koenig)
Newsgroups: comp.lang.c++
Subject: Re: const member functions ?
Message-ID: <9633@alice.UUCP>
Date: 18 Jul 89 12:53:21 GMT
References: <6590205@hplsla.HP.COM>
Organization: AT&T Bell Laboratories, Liberty Corner NJ
Lines: 35

In article <6590205@hplsla.HP.COM>, jima@hplsla.HP.COM (Jim Adcock) writes:

> Is there a way to declare a member function const -- IE to tell the compiler
> that the member function does not change the value of this nor *this

Yes [in 2.0]:

	class foo {
		int n;
	public:
		void setsize(int k) { n = k; }
		int getsize() const { return n; }
	};

If you say `const' in the declaration, and the definition isn't
in the same place, you must also say `const' in the definition:

	class bar {
		int n;
	public:
		void setsize(int);
		int getsize() const;
	};

	void bar::setsize(int k) { n = k; }
	void foo::getsize() const { return n; }

In a member function defined with `const' this way, `this' is
a pointer to a constant object.

It is meaningless to say `const' for a constructor or destructor:
they can operate on constants anyway.
-- 
				--Andrew Koenig
				  ark@europa.att.com