/* Program implements array as a stack. */

/* Program implements array as a stack. */
#include <stdio.h>
#include <conio.h>
#define MAX 10
struct stack
{
 int arr[MAX] ;
 int top ;
} ;
void initstack ( struct stack * ) ;
void push ( struct stack *, int item ) ;
int pop ( struct stack * ) ;
void main( )
{
 struct stack s ;
 int i ;
 clrscr( ) ;
 initstack ( &s ) ;
 push ( &s, 14 ) ;
 push ( &s, 20 ) ;
 push ( &s, 39 ) ;
 push ( &s, 2 ) ;
 push ( &s, 15 ) ;
 push ( &s, 7 ) ;
 i = pop ( &s ) ;
 printf ( "\n\nItem popped: %d", i ) ;
 i = pop ( &s ) ;
 printf ( "\nItem popped: %d", i ) ;
 i = pop ( &s ) ;
 printf ( "\nItem popped: %d", i ) ;
 i = pop ( &s ) ;
 printf ( "\nItem popped: %d", i ) ;
 i = pop ( &s ) ;
 printf ( "\nItem popped: %d", i ) ;
 getch( ) ;
}
/* intializes the stack */
void initstack ( struct stack *s )
{
 s -> top = -1 ;
}
/* adds an element to the stack */
void push ( struct stack *s, int item )
{
 if ( s -> top == MAX - 1 )
 {
  printf ( "\nStack is full." ) ;
  return ;
 }
 s -> top++ ;
 s -> arr[s ->top] = item ;
}
/* removes an element from the stack */
int pop ( struct stack *s )
{
 int data ;
 if ( s -> top == -1 )
 {
  printf ( "\nStack is empty." ) ;
  return NULL ;
 }
 data = s -> arr[s -> top] ;
 s -> top-- ;
 return data ;
}