🚀 go-pugleaf

In article <DDpG3H.88M@watserv3.uwaterloo.ca> amgaudra@ccnga.uwaterloo.ca (Alain M. Gaudrault) writes:
>
>	I'm having a tough time using the C qsort function within a C++
>class.  I have the following array of pointers:
>
>   static dataItemType** dataBlockVectorA = NULL;
>
>(which I initialize before the call to qsort, obviously), then further on
>down, I call:
>
>   qsort( dataBlockVectorA, dataBlockSize, sizeof( dataItemType*), pcompfunc);
>
>where pcompfunc is defined as follows:
>
>   int transformDataC::pcompfunc( dataItemType** item1, dataItemType** item2);
>
>As can be seen, the ordering function required by qsort is a member function,

Ok, it's a member function.  Now, think about this:  On what object 
is this function to operate?  Remember, member functions are invoked
by either ptr->memberfunc() or obj.memberfunc().  

The function specification for qsort requires two void * arguments.  The
way to comply with the spec is to do something like:

(Warning!  Untested code.)

int pcompfunc (const void * a, const void * b)
 {
   dataItemType * p1 = (dataItemType*)*a;
   dataItemType * p2 = (dataItemType*)*b;
   return p1->comparefunction(p2);
 }

Pete.