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From: jamesh@cs.umr.edu (James Hartley)
Newsgroups: comp.lang.c++
Subject: How are strings efficiently concatenated?
Message-ID: <2825@umriscc.isc.umr.edu>
Date: 16 Jun 91 06:55:59 GMT
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Organization: University of Missouri - Rolla
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Originator: jamesh@mcs213f.cs.umr.edu

Most implementations of strings that I have seen are centered around re-
tention of a character point in the class;  specifically,

        class string {
            char *str;
	    ...
        };

Because of the possibility of differing extents, memberwise initialization
of two strings is unwise.  For example,

        string s0, s1("one");
        s0 = s1;

s0 should dynamically allocate space for a copy of "one" rather than receive
a copy of the pointer to "one".

How is one to reclaim heapspace when concatenating strings together as in:

        string s2("two");
        s0 = s1 + s2;

The expression s1 + s2 will allocate space for "onetwo", but s0 will create
a new copy "onetwo".  How is the intermediate string deallocated?  What I
would really like to do is write efficient code for the following --

        s0 = s1 + s2 + s3;

No reasonable request will be turned down;  inquiring minds want to know...
-- 
James J. Hartley               _   /| Internet: jamesh@cs.umr.edu
Department of Computer Science \'o.O'   Bitnet: jamesh@cs.umr.edu@umrvmb.bitnet
University of Missouri - Rolla =(___)=    UUCP: ...!uunet!cs.umr.edu!jamesh
"Life is like an analogy..."      U    ACK!  PHFFT!