#include <iostream>
#include <cstddef>
#include <new>
#include <string.h>
 
template <typename T>
struct infinite_array {
    infinite_array();
    auto operator[](unsigned long long idx) -> T&;
 
    auto size() const -> unsigned long long;
    void resize(unsigned long long idx);
 
    private:
        T *data;
        unsigned long long array_length;
};
 
template <typename T>
void infinite_array<T> :: resize(unsigned long long idx)
{
    std::cout << "Resize with idx " << idx << std::endl;
    T *temp = new T[idx];
    memset(temp, 0, sizeof(T)*idx);
 
    for(int i = 0; i < array_length; ++i) {
            temp[i] = data[i];
            std::cout <<  temp[i] << " ";
    }
    std::cout << std::endl; 
    //std::copy(data, data+size(), temp);
    delete [] data;
 
    data = temp;
    array_length = idx;
 
}
 
template <typename T>
infinite_array<T> :: infinite_array() 
{
    data = NULL;
    array_length = 0;
}
 
template <typename T>
auto infinite_array<T> :: size() const -> unsigned long long {
    //array_length = sizeof(data)/sizeof(T);
    return array_length;
}
 
template <typename T>
auto infinite_array<T> :: operator[](unsigned long long idx) -> T& {
    //std::cout << "Accessing element at idx " << idx << std::endl;
    if(idx+1 > size()) {
        resize(idx+1);  
    }
    return data[idx];
}
 
 
int main() {
    infinite_array<int> ar; 
    for(int i = 0; i < 10; ++i) {
        ar[i] = i;
    }
 
    ar[30] = ar[31] = 10;
 
 
    for(int i = 0; i < ar.size(); ++i)
        std::cout << ar[i] << ' ';  
    std::cout << std::endl;
 
    return 0;
}

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