The dark orders of C++

There is one dark corner of the C++ language that is rarely touched by sunlight, and if a piece of code from these depths surfaces by any chance, a gang of hardcore developers immediately jumps on it and refactors it into digestible bits and bytes. Let’s consider, for example, the very simple case of why the a[2] and 2[a] expressions are equivalent when in C++, and a is an array of objects:

int main() {
    int a[16] = {0};
    a[2] = 3;
    3[a] = 4;
}

The preceding piece of code, despite the fact that it looks ugly, actually compiles. The reason is the following: in C++, the operator [] array subscript is defined in terms of pointer arithmetic. The a[i] expression is translated by the compiler into *(a + i), where a is a pointer to the first element of the array and i is the index. The i[a] expression at the end is also translated to the *(i + a) expression, where i is the index and a is...