The array Template Class (C++11)

The vector class has more capabilities than the built-in array type, but this comes at a cost of slightly less efficiency. If all you need is a fixed-size array, it could be advantageous to use the built-in type. However, that has its own costs of lessened convenience and safety. C++11 responded to this situation by adding the array template class, which is part of the std namespace. Like the built-in type, an array object has a fixed size and uses the stack (or else static memory allocation) instead of the free store, so it shares the efficiency of built-in arrays. To this it adds convenience and additional safety. To create an array object, you need to include the array header file. The syntax is a bit different from that for a vector:

#include <array>
...
using namespace std;
array<int, 5> ai;   // create array object of 5 ints
array<double, 4> ad = {1.2, 2.1, 3.43. 4.3};

More general, the following declaration creates an array object arr with n_elem elements of typeName:

array<typeName, n_elem> arr;

Unlike the case for vector, n_elem can’t be a variable.

With C++11, you can use list-initialization with vector and array objects. However, that was not an option with C++98 vector objects.