Re: Restrictions on qsort compare function?

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Article #4918

#4918

From: T.E.Dickey
Date: Wed, 20 Mar 1996 13:47

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James Bonfield (jkb@mrc-lmb.cam.ac.uk) wrote:
: Are there any limitations on what the sort function passed over to qsort can
: do or return? I know it's meant to return < 0, 0 or > 0 for the various
: compare operations, but which you return is purely up to your own comparison
: system.
In general, qsort will malfunction (at the least, you can get incorrect
sorting!) if

	compare(a,b) > 0 && compare(b,a) >= 0
or
	compare(b,a) > 0 && compare(a,b) >= 0

because it's not able to put the elements into disjoint sets.

-- 
Thomas E. Dickey
dickey@clark.net

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From: dickey@clark.net (T.E.Dickey)
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Subject: Re: Restrictions on qsort compare function?
Date: 20 Mar 1996 13:47:52 GMT
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