error: invalid use of member (did you forget the '&' ?)

[AndroidZ]

I'm getting this error on lines 77 and 84 of intstack.cpp. I spent an hour searching the web but I'm still not sure what to do. Any hints?

intstack.h

#pragma once

#include <stdlib.h>
class IntStack
{
    int INITIAL_SIZE;
    int stack_size;
    int* st_arr;
public:
    int stack_capacity;
    //default constructor
    IntStack() : INITIAL_SIZE(100), st_arr(new int [INITIAL_SIZE]) {
        stack_capacity = INITIAL_SIZE;
    }
    //destructor
    ~IntStack() {delete [] st_arr;}
    void reset();
    void push(int n);
    void push(int a[], size_t array_size);
    int pop();
    void pop(int a[], size_t n);
    int top();
    size_t size();
    size_t capacity();
    void double_capacity();
    //int* allocate(int num);
    //void deallocate( int* old);
    bool is_full();
    bool is_empty();
    friend IntStack print_stack(IntStack* pstack);
};

main.cpp

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

int main()
{
    IntStack stack;
    stack.reset();
    print_stack(&stack);

    cout << stack.stack_capacity;
    return 0;
}

intstack.cpp

#include "intstack.h"
#include <iostream>

using namespace std;

IntStack print_stack(IntStack* pstack){
    for (int i = 0; i < pstack->stack_size; i++){
        cout << pstack->st_arr[i] << "\n";
    }
}

int IntStack::top(){
    stack_size--;
    int temp = stack_size;
    stack_size++;
    return st_arr[temp];
}

size_t IntStack::size(){
    return stack_size;
}

size_t IntStack::capacity(){
    return stack_capacity;
}

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

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

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

int IntStack::pop(){
    //if stack is empty, int cannot be set to null, signal error
    if (stack_size == 0){
        cerr << "STACK EMPTY\n";
    }
    else
    //decrement to previous stack index then set it to NULL
    --stack_size;
    int temp = st_arr[stack_size];
    st_arr[stack_size] = NULL;
    return temp;
}

void IntStack::pop( int a[], size_t n ){
    stack_size--;
    for (int idx = 0; idx < n; idx++){
            a[idx] = st_arr[stack_size];
            st_arr[stack_size] = NULL;
        if(stack_size>0)stack_size--;
    }
    //for (i = 0; st_arr[i] != NULL; i++);
    //cout << "after popping, i is " << i << "\n"; //DB
}

int* allocate(int num);
void deallocate(int* old);

void IntStack::double_capacity(){
    int* new_mem = allocate(stack_capacity * 2);

    for (int i = 0; i < stack_size; i++){
        new_mem[i] = st_arr[i];
    }
    deallocate(st_arr);
    st_arr = new_mem;
    stack_capacity *= 2;
}


int* allocate(int num){
    int* new_mem = new int[num];
    return new_mem;
}

void deallocate(int* old){
    delete[] old;
}

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

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

[helios]

You're using capacity as a data member when it's actually a function. You probably meant to use stack_capacity.

By the way, IntStack::allocate() and IntStack::deallocate() shouldn't be member functions of IntStack. They don't use the object at all. At most, they should be static member functions.

[AndroidZ]

Fixed all of that, thanks.

I'm now running into errors saying all of my functions have been previously defined. Something to do with my includes? I can't spot the mistake. intstack.cpp is only included once and I have #pragma once guarding intstack.h