Can I define in C++ an array operator that takes multiple arguments? I tried it like this:
const T& operator[](const int i, const int j, const int k) const{
return m_cells[k*m_resSqr+j*m_res+i];
}
T& operator[](const int i, const int j, const int k){
return m_cells[k*m_resSqr+j*m_res+i];
}
But I'm getting this error:
error C2804 binary operator '[' has too many parameters
Prior to C++23, you could not overload operator[] to accept multiple arguments. As a workaround, you instead can overload operator(). (See How do I create a subscript operator for a Matrix class? from the C++ FAQ.)
From C++23, as mentioned in a (deleted) answer by cigien, multiple subscript arguments can be passed to operator[] directly. See this demo from the cppreference page.
It is not possible to overload the [] operator to accept multiple arguments, but an alternative is to use the proxy pattern.
In two words: a[x][y], the first expression (a[x]) would return a different type, named proxy type, which would have another operator[]. It would call something like _storedReferenceToOriginalObject->At(x,y) of the original class.
You will not be able to do a[x,y], but I guess you wanted to overload the usual C++-style 2D array syntax anyway.
Edit: as pointed in comment, in C++20 operator comma will be deprecated, so as the answer below.
You can't overload operator[], but you can fake it by overloading operator, instead.
Following your code it becomes:
T& operator,(const int i, const int j, const int k){
return m_cells[k*m_resSqr+j*m_res+i];
}
now you'll be able to call
something[1, 2, 3]
You can extend it using templates, templates with variadic arguments, std::pair or std::tuple depending on your use case and C++ version