s/*
Modified : Michael Robinson
Program  : stack.c
Purpose  : stack and memory dump simulator 
           To present push and pop on a stack, and memory dump 
           also show "for" loop as an endeless loop
Updated  : 03-22-2011
*/



#include<stdio.h>
 
int main()
{
    int a[10];//size of the stack  
    int i;

    printf("To pop enter -1   to exit enter  999\n");


    for(i = 0;;) //this is  an endless loop
    {
          printf("Push ");
          scanf("%d", &a[i]);

          if(a[i] == 999) //exit "for" loop and dump memory
          {
		break;
          }

          if( (i > 9)  && a[i] != -1  && a[i] != 999 )
          {
               printf(" Stack is FULL, I can not accept %d, you need to pop or exit\n", a[i] );
               continue;
          }

          if(a[i] == -1) //to pop the stack
          {
              if(i == 0) //at the bottom of the stack so it is empty
              {
                printf("Underflow\n"); //describes an error nothing to pop
              }
              else
              {
                printf("pop = %d\n", a[--i]); // 
              }
           }
           else
           {
              i++;
           }
    }

    //dump memory (stack)
    printf("\n Memory (stack) Dump\n");
    int x;
    for(x=i-1; x >= 0; x--)
    {
	printf(" stack address %d, contains %d\n", x, a[x] );
    } 

}