stack_implementation.cpp

#include <stdlib.h>
#include <iostream>
/*
stack is a linear data structure that follows the principle of Last In First Out (LIFO)
last element inserted inside the stack is removed first
*/
using namespace std;
#define MAX 10
int size = 0;
struct stack {
  int items[MAX];
  int top;
};
typedef struct stack st;
void createEmptyStack(st *s) {
  s->top = -1;
}
int isfull(st *s) {
  if (s->top == MAX - 1)
    return 1;
  else
    return 0;
}
int isempty(st *s) {
  if (s->top == -1)
    return 1;
  else
    return 0;
}
void push(st *s, int newitem) {
  if (isfull(s)) {
    cout << "STACK FULL";
  } else {
    s->top++;
    s->items[s->top] = newitem;
  }
  size++;
}
void pop(st *s) {
  if (isempty(s)) {
    cout << "\n STACK EMPTY \n";
  } else {
    cout << "Item popped= " << s->items[s->top];
    s->top--;
  }
  size--;
  cout << endl;
}
void printStack(st *s) {
  printf("Stack: ");
  for (int i = 0; i < size; i++) {
    cout << s->items[i] << " ";
  }
  cout << endl;
}
int main() {
  int ch;
  st *s = (st *)malloc(sizeof(st));
  createEmptyStack(s);
  push(s, 1);
  push(s, 2);
  push(s, 3);
  push(s, 4);
  printStack(s);
  pop(s);
  cout << "\nAfter popping out\n";
  printStack(s);
}