#include<iostream>

using namespace std;

#define STACKSIZE 10

struct a_stack
{
    int top = 0;
    int data[STACKSIZE];
};

bool is_full(struct a_stack);
bool is_stack_empty(struct a_stack);
void showstack(struct a_stack);
void init(struct a_stack*);
void push(struct a_stack*, int);
int  pop(struct a_stack*);

int main()
{
    struct a_stack my_stack;
    int i = 0;
    int x = 0;
    char expression[20] = "324121.";

    init(&my_stack);

    i = 0;
    while (expression[i] != '.')
    {
        switch (expression[i])
        {
        case '0': push(&my_stack, 0); break;
        case '1': push(&my_stack, 1); break;
        case '2': push(&my_stack, 2); break;
        case '3': push(&my_stack, 3); break;
        case '4': push(&my_stack, 4); break;
        case '5': push(&my_stack, 5); break;
        case '6': push(&my_stack, 6); break;
        case '7': push(&my_stack, 7); break;
        case '8': push(&my_stack, 8); break;
        case '9': push(&my_stack, 9); break;
        case '*' : push(&my_stack, pop(&my_stack) * pop(&my_stack)); break;
        case '/': push(&my_stack, pop(&my_stack) / pop(&my_stack)); break;
        case '+': push(&my_stack, pop(&my_stack) + pop(&my_stack)); break;
        case '-': push(&my_stack, pop(&my_stack) - pop(&my_stack)); break;
        default: std::cout << "Not Implemented expression "<< i << expression[i] << std::endl;
        }
        i++;
    }
    showstack(my_stack);
    //
    // result of computation should be at top of stack
    // pop result and print it so that the user knows.
    return 0;
}

int  pop(struct a_stack* my_stack)
{
    int x = 0;
    my_stack->top--;
    x = my_stack->data[my_stack->top];
    my_stack->data[my_stack->top] = -1;
    return x;
}


void push(struct a_stack* my_stack, int item)
{
    my_stack->data[my_stack->top] = item;
    my_stack->top++;
}

void init(struct a_stack* my_stack)
{
    my_stack->top = 0;
}


void showstack(struct a_stack my_stack)
{
    cout << my_stack.top << " items " << endl;
    for (int i = 0; i < my_stack.top; i++)
        cout << i << "  :  " << my_stack.data[i] << endl;
}

bool is_stack_empty(struct a_stack my_stack)
{
    if (my_stack.top == 0)
        return true;
    else
        return false;
}

bool is_full(struct a_stack my_stack)
{
    if (my_stack.top > STACKSIZE - 1)
        return true;
    else
        return false;

}