What are the different types of iterators in C++ std::vector?

What are the different types of iterators in C++ std::vector?

In C++, std::vector provides several types of iterators: random access iterators, const iterators, and reverse iterators. Random access iterators allow you to access elements in constant time using offsets, while const iterators provide read-only access to the elements. Reverse iterators allow you to iterate through the vector in reverse order.

Can you explain how to use a reverse iterator with std::vector?

Sure! To use a reverse iterator with std::vector, you can use the rbegin() and rend() member functions. For example:

std::vector<int> vec = {1, 2, 3, 4, 5};
for (auto it = vec.rbegin(); it != vec.rend(); ++it) {
    std::cout << *it << ' ';
}

This will print the elements in reverse order.

What is the difference between const_iterator and iterator?

The main difference is that an iterator allows you to modify the elements of the vector, while a const_iterator provides read-only access. This means you can change the value of elements using an iterator, but not with a const_iterator.

Are there any performance differences between these iterators?

Generally, there are no significant performance differences between the different types of iterators in std::vector, as they all provide constant time access. However, using const_iterators can prevent accidental modifications, which can be beneficial for code safety.