Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!usc!sdd.hp.com!wuarchive!emory!rsiatl!stan
From: stan@Dixie.Com (Stan Brown)
Newsgroups: comp.lang.c
Subject: Pointers To Structures Question (qsort)
Keywords: qsort
Message-ID: <7519@rsiatl.Dixie.Com>
Date: 2 Mar 91 22:16:36 GMT
Distribution: usa
Organization: Dixie Communications Services
Lines: 67


	I have a problem with a program that I am working on.   It compiles
and works correctly, but generates a compiler warning message of the form

warning : structure/union or structure/union pointer required

	Since I plan on moving this code to a new machine when I get it I
dam concerned aboyt portabilty.

	The environment that I am working in is a version 7 machine (Fortune
32:16 if you ever heard of it).

	What rellay pzzles me is that I think there is one more level of
inderction in the compare function than I think is required, yet it works.
If someone could explain my miscomception here, I would greatly
appreciate it.

** The structure

        /* structure of fileing location information    */
struct  file_loc  {
	char *key;
	char *description;
	char *long_description;
	int	qty;
	}  ;

** The array decleration

main(argc,argv)
int argc;
char *argv[];
{
struct file_loc *array_of_loc_struct[MAX_LOCS];

** The call from main

sort_loc(array_of_loc_struct);

** The call to qsort

void sort_loc(array)
struct file_loc *array[];
{
extern int cmp_loca();
int qty = 0;

	while(array[++qty] != NULL)        /* Find Qty */
		;

	 qsort(&array[0], qty, sizeof(struct series *), cmp_loca); 
}


** The compare function

int cmp_loca(struct1,struct2)
void  *struct1;
void  *struct2;
{
	return strcmp((*(struct file_loc *)struct1)->key, (*(struct file_loc *)struct2)->key);
}


-- 
Stan Brown	P. c. Design 	404-363-2303
ateche!sdba!stan				"vi forever"