Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!virtech!cpcahil
From: cpcahil@virtech.UUCP (Conor P. Cahill)
Newsgroups: comp.lang.c
Subject: Re: qsorting & managing struct arrays, pointer arrays
Keywords: can qsort accept array of pointers to struct?
Message-ID: <1298@virtech.UUCP>
Date: 20 Oct 89 23:33:47 GMT
References: <169@cica.cica.indiana.edu>
Distribution: na
Organization: Virtual Technologies Inc
Lines: 41

In article <169@cica.cica.indiana.edu>, burleigh@cica.cica.indiana.edu (Frank Burleigh) writes:

>    Can the standard qsort accept not the array of structures, but
>    the array of pointers to structure members?  If yes, how then
>    can the declaration of ncmp (the compare function) be changed
>    to accept two elements ([i], [j]) from the array of pointers,

Your example would be changed to something like:

    typedef struct struct_name {...} struct_name;
    struct_name *list[MAXSIZE], **s_start, *s_one, *s_two;
                ^               ^
 
    main()
    {
       /*allocate and load the array of struct here*/
         ^^^^^^^^^^^^
       s_start = list;
       /*other business*/
       qsort( s_start, s_members, sizeof( struct_name *), ncmp );
	                                              ^
    }
 
    int ncmp( struct_name ** s_one, struct_name ** s_two )
                           ^                     ^
    {
       return strcmp( (*s_one)->elem, (*s_two)->elem );
                      ^^^^^^^^        ^^^^^^^^
    }


NOTE: I have not compiled the above, but you should get the idea.




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