Are arrays in C++ same as C?

Question

Does the C++ compiler treat the arrays same way as in C?

E.g

In C,

• An array access using subscript operator is always interpreted as a pointer.
• In function argument, array declarations are treated as pointer to start of element.

Answer 1

Yes and no. Arrays work the same in both languages for the most part (C99 supports variable-length arrays, while C++ doesn't, and there may be a few other subtle differnces as well).

However, what you're saying isn't exactly true either. The compiler doesn't treat an array access as a pointer, not even in C. An array access can be more efficient in some cases, because the compiler has better information on aliasing available in the array case. In both C and C++, a plain pointer access means that the compiler has to assume that it may alias any other compatible type. If the compiler simply treated it as a pointer dereference, then this optimization opportunity would be lost.

Edit
As pointed out in a comment, the language standard does define array subscripting in terms of pointer arithmetics/dereferencing. Of course, actual compilers make use of the additional information that a pointer is really an array, so they're not treated exactly like pointers, but that could be considered an optimization beyond what the standard mandates.