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std::array(3) C++ Standard Libary std::array(3) NAME std::array - std::array Synopsis Defined in header <array> template< class T, (since C++11) std::size_t N > struct array; std::array is a container that encapsulates fixed size arrays. This container is an aggregate type with the same semantics as a struct holding a C-style array T[N] as its only non-static data member. Unlike a C- style array, it doesn't decay to T* automatically. As an aggregate type, it can be initialized with aggregate-initialization given at most N initializers that are con- vertible to T: std::array<int, 3> a = {1, 2, 3};. The struct combines the performance and accessibility of a C-style array with the benefits of a standard container, such as knowing its own size, sup- porting assignment, random access iterators, etc. std::array satisfies the requirements of Container and Reversible- Container except that default-constructed array is not empty and that the complexity of swapping is linear, satisfies the requirements of ContiguousContainer, (since C++17) and partially satisfies the requirements of Sequence- Container. 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. An array can also be used as a tuple of N elements of the same type. Template parameters T - element type Must be MoveConstructible and MoveAssignable. N - the number of elements in the array or 0. This section is incomplete Reason: Complete the descriptions of template parameters. Member types Member type Definition value_type T size_type std::size_t difference_type std::ptrdiff_t reference value_type& const_reference const value_type& pointer value_type* const_pointer const value_type* LegacyRandomAccessIterator and (until C++17) LegacyContiguousIterator to value_type LegacyRandomAccessIterator and (since C++17) LegacyContiguousIterator that is a Literal- Type (until C++20) iterator to value_type LegacyRandomAccessIterator, contiguous_iterator, and ConstexprIterator to (since C++20) value_type LegacyRandomAccessIterator and (until C++17) LegacyContiguousIterator to const value_type LegacyRandomAccessIterator and (since C++17) LegacyContiguousIterator that is a Literal- Type (until C++20) const_iterator to const value_type LegacyRandomAccessIterator, contiguous_iterator, and ConstexprIterator to (since C++20) const value_type reverse_iterator std::reverse_iterator<iterator> const_reverse_iterator std::reverse_iterator<const_iterator> Member functions Implicitly-defined member functions initializes the array following the rules of aggregate constructor initialization (note that default initializa- tion may result in (implicitly declared) indeterminate values for non-class T) (public member function) destructor destroys every element of the array (implicitly declared) (public member function) operator= overwrites every element of the array with the corresponding (implicitly declared) element of another array (public member function) Element access at access specified element with bounds checking (public member function) operator[] access specified element (public member function) front access the first element (public member function) back access the last element (public member function) data direct access to the underlying contiguous storage (public member function) Iterators begin returns an iterator to the beginning cbegin (public member function) end returns an iterator to the end cend (public member function) rbegin returns a reverse iterator to the beginning crbegin (public member function) rend returns a reverse iterator to the end crend (public member function) Capacity empty checks whether the container is empty (public member function) size returns the number of elements (public member function) max_size returns the maximum possible number of ele- ments (public member function) Operations fill fill the container with specified value (public member function) swap swaps the contents (public member function) Non-member functions operator== operator!= operator< operator<= operator> operator>= operator<=> lexicographically compares the values of two arrays (C++11) (function template) (C++11)(removed in C++20) (C++11)(removed in C++20) (C++11)(removed in C++20) (C++11)(removed in C++20) (C++11)(removed in C++20) (C++20) get(std::array) accesses an element of an array (C++11) (function template) std::swap(std::array) specializes the std::swap algorithm (C++11) (function template) to_array creates a std::array object from a built- in array (C++20) (function template) Helper classes std::tuple_size<std::array> obtains the size of an array (C++11) (class template specialization) std::tuple_element<std::array> obtains the type of the elements of array (C++11) (class template specialization) Deduction guides (since C++17) Example // Run this code #include <algorithm> #include <array> #include <iostream> #include <iterator> #include <string> int main() { // Construction uses aggregate initialization std::array<int, 3> a1{{1, 2, 3}}; // Double-braces required in C++11 prior to // the CWG 1270 revision (not needed in C++11 // after the revision and in C++14 and beyond) std::array<int, 3> a2 = {1, 2, 3}; // Double braces never required after = // Container operations are supported std::sort(a1.begin(), a1.end()); std::ranges::reverse_copy(a2, std::ostream_itera- tor<int>(std::cout, " ")); std::cout << '\n'; // Ranged for loop is supported std::array<std::string, 2> a3{"E", "\u018E"}; for (const auto& s : a3) std::cout << s << ' '; std::cout << '\n'; // Deduction guide for array creation (since C++17) [[maybe_unused]] std::array a4{3.0, 1.0, 4.0}; // std::array<dou- ble, 3> // Behavior of unspecified elements is the same as with built-in arrays [[maybe_unused]] std::array<int, 2> a5; // No list init, a5[0] and a5[1] // are default initialized [[maybe_unused]] std::array<int, 2> a6{}; // List init, both ele- ments are value // initialized, a6[0] = a6[1] = 0 [[maybe_unused]] std::array<int, 2> a7{1}; // List init, unspeci- fied element is value // initialized, a7[0] = 1, a7[1] = 0 } Output: 3 2 1 E See also make_array creates a std::array object whose size and optionally (library fundamentals TS v2) element type are deduced from the argu- ments (function template) Category: * Todo with reason http://cppreference.com 2024.06.10 std::array(3)
NAME | Synopsis | Template parameters | Member types | Member functions | Implicitly-defined member functions | Element access | Iterators | Capacity | Operations | Non-member functions | Helper classes | Example | Output: | See also | Category:
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