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From: shirley@iuvax.cs.indiana.edu (peter shirley)
Newsgroups: comp.lang.c++
Subject: Re: why is this program slow?
Message-ID: <1991Jan9.113134.26637@news.cs.indiana.edu>
Date: 9 Jan 91 06:31:03 GMT
References: <1991Jan9.002244.23398@news.cs.indiana.edu> <14167@ulysses.att.com>
Organization: Computer Science, Indiana University
Lines: 18

Several people on this group and by mail suggested I needed a +=
operation for vectors.  I tried this, and on our vax it got the C++
code to be as fast as the C code.  On a sparc, it was as fast with "big-O"
turned off, but the C code was much better with the optimizer on.  Maybe
cc was smart enough to change something like:

	a = 0;
	for (i=0; i < 1000000; i++)
	   a = a + 1;

to:

	a = 1000000;


Anyway, things are working great now.  Thank you all for the quick help!

pete shirley