#include <stdio.h>    /* C example */
#include <stdlib.h>
#include "stack.h"
#define STACK_MAX_SIZE 100

static int a[STACK_MAX_SIZE];
static size_t n = 0;  /* number of values in the stack; stack initially empty */

/* Push a value onto the stack. */

void push(int i)
{
	if (n == STACK_MAX_SIZE) {   /* overflow */
		fprintf(stderr, "Can't push when size %u == capacity %u.\n",
			n, STACK_MAX_SIZE);
		exit(EXIT_FAILURE);
	}

	a[n++] = i;
}

/* Pop a value off the stack. */

int pop(void)
{
	if (n == 0) {                /* underflow */
		fprintf(stderr, "Can't pop when size %u == 0.\n", n);
		exit(EXIT_FAILURE);
	}

	return a[--n];
}