stack implementation in c++ with struct

[simons]

Hi,

I am trying to implement a stack class which has struct data type as its private member. I am getiing the following error ,

bash-3.2$ g++ stack_str_arr.cpp
stack_str_arr.cpp: In member function ‘void stack::push(int)’:
stack_str_arr.cpp:39: error: ‘top’ was not declared in this scope
stack_str_arr.cpp: At global scope:
stack_str_arr.cpp:43: error: no ‘void stack::display()’ member function declared in class ‘stack’


I am a beginner, please let me know what mistake am making here.

  #include<iostream>

using namespace std;
#define MAX 5
class stack 
{
	public : 
		stack();
		void push(int);
		int pop();

	private :
		//struct st s ;
		struct st {
					int top;
					int arr[MAX];
				  } s;
};

stack::stack()
{
	s.top = -1;

}

void::stack::push(int elem)
{
	if(s.top == MAX-1)
	{
		cout<<"\nStack is full"<<endl;
	}
	else 
	{
		s.top++;
		s.arr[top] = elem;
	}
}

void::stack::display()
{
	for (int i=0; i<= MAX;i++)
	{
		cout<<s.arr[i]<<endl;
	}
}
int main()
{
	stack stobj;

	stobj.push(5);
	stobj.push(51);
	stobj.push(52);
	stobj.push(54);
	stobj.push(53);

	stobj.display();

}

[kbw]

void stack::push(int elem)
{
	if(s.top == MAX-1)
	{
		cout<<"\nStack is full"<<endl;
	}
	else 
	{
		s.top++;
		s.arr[s.top] = elem;
	}
}

EDIT: And change all those void::stack:: to void stack::.

[kannanmj]

@4 MAX is system (from limits header) macro. So replace it with ARR_MAX or something that sort of.

@35 top is a data member within struct st object s. So it has to be accessed through s, like: s.arr[s.top] = elem;

@main function. It has non-void return type (int). Include a return statment in the end.

Replace all void::stack::* with void stack::*

@For loop in display function. The arrange range should be 0 to ARR_MAX-1 i.e i=0; i<ARR_MAX.

All the above are fixed in the following code.

#include <iostream>
#define ARR_MAX 5

class stack 
{
  public : 
    stack();
    void push(int);
    void display(void);
    int pop();

  private :
    struct st {
      int top;
      int arr[ARR_MAX];
    } s;
};

stack::stack()
{
  s.top = -1;
}

void::stack::push(int elem)
{
  if(s.top == ARR_MAX-1)
  {
    std::cout << "\nStack is full" << std::endl;
  }
  else 
  {
    s.top++;
    s.arr[s.top] = elem;
  }
}

void::stack::display()
{
  for (int i=0; i< ARR_MAX;i++)
  {
    std::cout << s.arr[i] << std::endl;
  }
}
int main()
{
  stack stobj;

  stobj.push(1);
  stobj.push(2);
  stobj.push(3);
  stobj.push(4);
  stobj.push(5);

  stobj.display();
  return 0;
}