heapchecknode()         Check a Node on the Heap

 #include   <alloc.h>

 int heapchecknode(node);
 void *node;         Node to check

        This function checks and verifies a single node in the heap. The
        possible return values are:

                _HEAPEMPTY      Heap is empty.
                _HEAPCORRUPT    Heap has been corrupted.
                _BADNODE        Node could not be found.
                _FREENTRY       Node is a free block.
                _USEDENTRY      Node is a used block.

       Returns:     Greater than zero for success; negative otherwise.

   -------------------------------- Example ---------------------------------
        This example checks a single node on the heap.

     #include <stdio.h>
     #include <alloc.h>

     int main(void)
     {
       if(heapchecknode(malloc(1000)) < 0)
               printf("Heap problems.\n");

       return 0;
     }