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From: jha@spodv5.UUCP (Johan Harsta)
Newsgroups: comp.lang.c,comp.unix.xenix
Subject: Re: qsort() - HELP
Message-ID: <144@spodv5.UUCP>
Date: 13 Feb 90 13:10:46 GMT
References: <5916@ozdaltx.UUCP>
Organization: Philips TDS, Stockholm, Sweden
Lines: 45

In article <5916@ozdaltx.UUCP>, root@ozdaltx.UUCP (root) writes:
> After going over the manuals more times than I'd like, I still can't
> figure out how to get qsort() (S) to operate.  The example shows
> something like:
> 
> 	void qsort(base, nel, width, compar)
> 	char *base
> 	unsigned nel, width
> 	int (*compar)()
> 
> Is base supposed to be an array?
	- 'base' should be a pointer to the base of the table, and of type
	pointer to an element in the table, casted to a pointer to character
> nel & width are self-explanitory
> What is compar() looking for or how is it assigned?
	- 'compar' is supplied by you; e.g. 'strcmp' or a modified version
	of it

E.g.:
	struct ELEMENT buffer[nele];

	sort_buf (&buffer[0], nele);

	void
	sort_buffer (base, nele)
		struct ELEMENT *base;
		int nele;
	{	
		qsort ((char *) base, 
			(unsigned) nele, 
			(unsigned) sizeof (struct ELEMENT),
			sorting_alg);
		return;
	}

	int
	sorting_alg (arg1, arg2)
		char *arg1;
		char *arg2;
	{
		return (strncmp (arg1, arg2, MAX_RELEVANT_CHARACTERS));
	}

	Something like the above should work, good luck!	

	/Johan Harsta, Programator Uppsala AB, Sweden (consultant for Philips)