Element count of an array in C++

Question

Let\'s say I have an array arr. When would the following not give the number of elements of the array: sizeof(arr) / sizeof(arr[0])?

I can

Answer 1

First off, you can circumvent that problem by using std::vector instead of an array. Second, if you put objects of a derived class into an array of a super class, you will experience slicing, but the good news is, your formula will work. Polymorphic collections in C++ are achieved using pointers. There are three major options here:

• normal pointers
• a collection of boost::shared_ptr
• a Boost.Pointer Container