Passing an object as a pointer?

[ZGalhardo]

#include <iostream>
#include <stdlib.h>
using namespace std;

class IntStack{
    static const int INITIAL_SIZE = 100;
    int i;
    int st_arr[INITIAL_SIZE];
public:
    void reset();
    void push(int n);
    void push(int a[], size_t array_size);
    int pop();
    void pop(int a[], size_t n);
    bool is_full();
    bool is_empty();
    friend IntStack print_stack(IntStack* pstack);
};

IntStack print_stack(IntStack* pstack){
    
    for (int i = 0; i < 100; i++){
        //cout << pstack;
    }
}
int main()
{
    int arr[5] = {1,2,3,4,5};
    IntStack stack;
    stack.reset();
    stack.push(9);
    stack.pop();
    stack.push(arr, 5);
    stack.pop(arr, 5);
    print_stack(&stack);
    return 0;
}

void IntStack::reset(){
    //loop through the stack and set each element to NULL
    for (i = 0; i < INITIAL_SIZE; i++){
        st_arr[i] = NULL;
    }
    i = 0;
}

void IntStack::push(int n){
    //if stack is full, int cannot be pushed, signal error
    if (i == 100){
        cerr << "error: stack is full, cannot push another int";
        exit(1);
    }
    //set current element of stack to pushed int then increment index
    st_arr[i] = n;
    i++;
}

void IntStack::push( int arr[], size_t array_size ){
    for (int idx = 0; idx < array_size; idx++){
        push(arr[idx]);
    }
}

int IntStack::pop(){
    //if stack is empty, int cannot be set to null, signal error
    if (i == 0){
        cerr << "error: stack is empty, cannot delete element";
        exit(1);
    }
    //decrement to previous stack index then set it to NULL
    --i;
    st_arr[i] = NULL;
}

void IntStack::pop( int a[], size_t n ){
    i--;
    for (int idx = 0; idx < n; idx++){
            st_arr[i] = a[idx];
            i--;
    }
    for (i = 0; st_arr[i] != NULL; i++){} //figure out how to make this line unnecessary
}

bool IntStack::is_full(){
    if(i == 100)
        return true;
    else
        return false;
}

bool IntStack::is_empty(){
    if(i != 0)
        return false;
    else
        return true;
}

[EricDu]

Just hints:

- declare print_stack() as a friend in IntStack class's definition.
- in body of print_stack(), you can directly access all of IntStack's private members via pointer pstack.
- in main(), pass stack's address to print_stack() to complete your goal.

ZGalhardo wrote:

I'm not sure how to pass stack to the print_stack function.

print_stack(&stack);

[ZGalhardo]

I forgot to mention, it has to be a global function.
Declare it as a friend of what? IntStack? The compiler throws me an error in that case, stating it's implicitly a friend, which makes sense.


EDIT: nvm, I left void in there and it was throwing it off. Continuing work.

[ZGalhardo]

Now I need to dereference the pointer, but how, and to what? How do I access the stack?
Got it, was using * instead of ->. Thanks for the help.