/*------------------------------------------------------------------*/
/* stackbad.h (A Stack ADT Interface)                               */
/* Author: Bob Dondero                                              */
/* A Stack ADT interface that reveals the data structure to clients */
/*------------------------------------------------------------------*/

#ifndef STACKBAD_INCLUDED
#define STACKBAD_INCLUDED

/* A Stack is a last-in-first-out collection of doubles. */

struct Stack
{
   /* The array in which items are stored. */
   double *pdArray;

   /* The index one beyond the top element. */
   int iTop;

   /* The number of elements in the array. */
   int iPhysLength;
};

struct Stack *Stack_new(void);
/* Return the address of a new Stack. */

void Stack_free(struct Stack *psStack);
/* Free psStack. */

void Stack_push(struct Stack *psStack, double dItem);
/* Push dItem onto *psStack.
   It is a checked runtime error for psStack to be NULL. */

double Stack_pop(struct Stack *psStack);
/* Pop *psStack, and return the popped item.
   It is a checked runtime error for psStack to be NULL
   or for *psStack to be empty. */

int Stack_isEmpty(struct Stack *psStack);
/* Return 1 (TRUE) iff *psStack is empty.
   It is a checked runtime error for psStack to be NULL. */

#endif