OLiSwEll

/*  Write a Program to perform the following operation stack using array. */
/* PUSH, POP, ISEMPTY, ISFULL, PEEP   */
#define max 4
void push();
void pop();
int isempty();
int isfull();
void peep();
void disp();
int top=-1,stack[max];
void main()
{
  int ret,s1,choice;
  clrscr();
do
{
  printf("\n\n1 : Push element in Stack.\n");
  printf("2 : Pop an element from stack.\n");
  printf("3 : Peep an element into stack.\n");
  printf("4 : Exit from Program.\n");
  printf("Enter your choice :  ");
  scanf("%d",&choice);

  switch(choice)
   {
    case 1:
        ret = isfull();
          if(ret!=1)
           push();
           disp();
         break;
    case 2:
        ret = isempty();
         if(ret != 1)
           pop();
           disp();
         break;
    case 3:
         ret = isempty();
          if(ret != 1)
           peep();
           disp();
         break;
    case 4:
         exit();
    default :
        printf("\n\n\t\t######## INVALID CHOICE ##########\n\n");
   }

}while(s1);

}



int isfull()
{
  if(top == max)
   {
    printf("\n\n\t\t####### STCK IS OVERFLOW #########\n\n");
    return 1;
   }
  else
   return 0;
}


int isempty()
{
  if(top == -1)
   {
    printf("\n\n\t\t####### STCK IS UNDERFLOW #########\n\n");
    return 1;
   }
  else
   return 0;
}

void push()
{
  int item;
  printf("\nEnter an Integer value : ");
  scanf("%d",&item);
  top = top + 1;
  stack[top] = item;
}

void pop()
{
  int item;
  item = stack[top];
  top = top -1;
  printf("\n\n\t\t%d is deleted\n",item);
}


void peep()
{
  int item,p;
  printf("\n\nEnter position : ");
  scanf("%d",&p);
   printf("\n\nYour selected Element is %d ",stack[top-p+1]);
}

void disp()
{
  int i;
  printf("\n\nStack Contains : ");
  for(i=0;i<=top;i++)
   printf("%d ",stack[i]);
}