PRODUCT  :  C++                                    NUMBER  :  659
  VERSION  :  All
       OS  :  PC DOS
     DATE  :  September 17, 1991                       PAGE  :  1/1

    TITLE  :  An Example of Using qsort() in C++ Mode




  Due to the strict type checking enforced by the C++ language, one
  must  insure  that  the  types  of the parameters to qsort  match
  exactly.

  The  types  of  the parameters passed to the compare function are
  the area for grief here.  By using a typedef which  typecasts the
  compare  function  to  have the types  required  by  the  ANSI  C
  prototype for qsort(), C++ can be made to accept our code.


  //---------------------------------------------------------------
  // QSORTX.CPP - using qsort() in C++ mode

  #include <stdlib.h>

  typedef int (*cmp_func)(const void *, const void *);

  int compare( const int *one, const int *two )
  {
     if (*one > *two)
        return  -1
     else
        return 1;
  } // end of compare()

  int a[3] = { 50, 10, 20 };

  main()
  {
     qsort(a, 3, sizeof(a[0]), compare);   // Does not compile in C++
     qsort(a, 3, sizeof(a[0]), (cmp_func)compare);  // Does compile
  } // end of main()