#include <iostream>
#include <vector>
using namespace std;

// This is a globally known value
// we want to substract the "next" button from max items.
const int max_items = 32-1;

void ShowPage(int page, vector<int> const & items)
{
    int count = 0; // added items count
    for (int i = page*max_items; i < items.size(); ++i) // go through all items, we want to start from page beginning
    {
        cout << "Item number: " << i << endl;
        ++count; // added an item, increase count of items
        if (count >= max_items)
        {
            // we are at limit, add next button and stop adding items
            cout << "Next page" << endl;
            break;
        }
    }
    // Send menu()
}

int main() {
    /*
    Through for loops and such you have gathered all items the player has in a list called "items".
    These items can be for example pointers to the items you get from GetItemByPos or similar.
    These are all the valid items to be shown in the menu.
    */
    vector<int> items = {};
    for (int i = 0; i < 100; ++i)
        items.push_back(i);

    ShowPage(0, items);
    ShowPage(1, items);
    ShowPage(100, items);
}