///////    Treating arbitrary data types    ///////
#include <iostream.h>

typedef int (* END_FN)(void *, int);

arblen(void *any,  END_FN is_end)
{   int len=0;
        while ( ! is_end(any,len) ) len++;
        return(len);
}

int int_end(int *a, int i)
{       return( a[i] == -1 );
}

int str_end(char *a, int i)
{       return( a[i] == '\0' );
}


int main()
{ char a[]="abcdefg";
  int b[]={0,1,2,3,4,-1};
  int i;
  void * foo;
      i = arblen(a, END_FN(str_end) );                // length 7 
      cout << "length of string = " << i << endl;
      i = arblen(b, END_FN(int_end) );                // length 5 
      cout << "length of int array = " << i << endl;
      return(0);
}