Difference between revisions of "cpp/container/array"

Revision as of 13:01, 16 April 2013

std::array is a container that encapsulates constant size arrays.

This struct has the same aggregate type semantics as a C-style array. The size and efficiency of array<T,N> for some number of elements is equivalent to size and efficiency of the corresponding C-style array T[N]. The struct provides the benefits of a standard container, such as knowing its own size, supporting assignment, random access iterators, etc.

There is a special case for a zero-length array (N == 0). In that case, array.begin() == array.end(), which is some unique value. The effect of calling front() or back() on a zero-sized array is undefined.

array is an aggregate (it has no user-defined constructors and no private or protected members), which allows it to use aggregate-initialization.

An array can also be used as a tuple of N elements of the same type.

Member types

Member functions

Non-member functions

Helper classes

Example

#include <string>
#include <iterator>
#include <iostream>
#include <algorithm>
#include <array>
 
int main()
{
    // construction uses aggregate initialization
    std::array<int, 3> a1{ {1,2,3} };  // double-braces required
    std::array<int, 3> a2 = {1, 2, 3}; // except after =
    std::array<std::string, 2> a3 = { {std::string("a"), "b"} };
 
    // container operations are supported
    std::sort(a1.begin(), a1.end());
    std::reverse_copy(a2.begin(), a2.end(), std::ostream_iterator<int>(std::cout, " "));
 
    // ranged for loop is supported
    for(auto& s: a3)
        std::cout << s << ' ';
}

3 2 1 a b