Array indexing starting at a number not 0

Question

Is it possible to start an array at an index not zero...I.E. you have an array a[35], of 35 elements, now I want to index at say starting 100, so the numbers would be a[100], a[

Answer 1

C++ provides quite a bit more than C in this respect. You can overload operator[] to do the subtraction, and if you want report an error (e.g., throw an exception) if the subscript is out of range.

As a minimal demo, consider the following:

#include 
#include 

template 
class array {
    T data[upper-lower];
public:
    T &operator[](int index) { 
        if (index < lower || index >= upper)
            throw std::range_error("Index out of range");
        return data[index-lower]; 
    }
    T *begin() { return data; }
    T *end() { return data + (upper-lower); }
};

int main() {
    array data;

    for (int i=-3; i<5; i++)
        data[i] = i;

    for (auto const &i : data) 
        std::cout << i << "\t";
    std::cout << "\n";
}