Compare Generic Type

[mott747]

I'm working to learn C. I've into a problem that I'm not sure how to
solve. I'm implementing a basic binary tree but I don't want it to be
restricted to a particular data type. I seemed to be able to get
around this by making the data type stored a pointer to void. But then
this introduces the problem that I can't compare the values being
pointed to. Can anyone give me any tips?

[Dave Vandervies]

In article <c6*************************@posting.google.com> ,
<mo*****@yahoo.com> wrote:

I'm working to learn C. I've into a problem that I'm not sure how to
solve. I'm implementing a basic binary tree but I don't want it to be
restricted to a particular data type. I seemed to be able to get
around this by making the data type stored a pointer to void. But then
this introduces the problem that I can't compare the values being
pointed to. Can anyone give me any tips?

Let the user give you a comparison function, the way qsort and bsearch do.

For bonus points, use a comparison function with the same interface,
so the same function can be used for all three.
dave

--
Dave Vandervies dj******@csclub.uwaterloo.ca
80% of all questions that begin with the word 'why' can be answered
with the simple sentence 'people are stupid.'
--Shamelessly Stolen From Mike in uw.general

[Martin Ambuhl]

mo*****@yahoo.com wrote:

I'm working to learn C. I've into a problem that I'm not sure how to
solve. I'm implementing a basic binary tree but I don't want it to be
restricted to a particular data type. I seemed to be able to get
around this by making the data type stored a pointer to void. But then
this introduces the problem that I can't compare the values being
pointed to. Can anyone give me any tips?

struct cell {
int type; /* pointer to a property list is even better */
void *valueptr; /* this can, of course, hold a pointer to
struct cell */
}

struct leaf {
struct cell *cdr;
struct cell *car;
}