In C++, the Standard Template Library (STL) provides several sequence containers, which are data structures that store elements in a linear sequence. One of these containers is the array container, which provides a fixed-size array with a constant size that is known at compile time.

An array container can be declared as follows:

#include <array>
std::array<int, 5> myArray; // an array of 5 integers

Here, std::array is a templated class that takes two template parameters: the type of the elements to store (int in this case), and the size of the array (5 in this case).

The array container provides several member functions, including:

• at(): returns a reference to the element at a specified position, with bounds checking.
• operator[]: returns a reference to the element at a specified position, without bounds checking.
• front(): returns a reference to the first element.
• back(): returns a reference to the last element.
• size(): returns the number of elements in the array.
• empty(): returns true if the array is empty.
• fill(): fills the array with a specified value.

array containers can be useful in situations where a fixed number of elements are required, and where the size of the array is known at compile time. They are also more efficient than dynamic arrays, since they do not require dynamic memory allocation and deallocation.

Here is an example of using the array container:

#include <iostream>
#include <array>

int main()
{
  std::array<int, 5> myArray = {1, 2, 3, 4, 5};

  // Access elements
  std::cout << "myArray[2] = " << myArray[2] << std::endl;
  std::cout << "myArray.front() = " << myArray.front() << std::endl;
  std::cout << "myArray.back() = " << myArray.back() << std::endl;

  // Fill array with a value
  myArray.fill(0);

  // Output array
  for (int i = 0; i < myArray.size(); ++i)
    std::cout << myArray[i] << ' ';
  std::cout << std::endl;

  return 0;
}