winrt::array_view struct template (C++/WinRT)

A view, or span, of a contiguous series of values. For more examples and info about winrt::array_view, see Standard C++ data types and C++/WinRT.

Syntax

template <typename T>
struct array_view

Template parameters

typename T The type of the values (elements) that the array_view views, or spans.

Requirements

Minimum supported SDK: Windows SDK version 10.0.17134.0 (Windows 10, version 1803)

Namespace: winrt

Header: %WindowsSdkDir%Include<WindowsTargetPlatformVersion>\cppwinrt\winrt\base.h (included by default)

Member type aliases

Alias name	Type
array_view::value_type	A synonym for the typename T template parameter.
array_view::size_type	A synonym for uint32_t.
array_view::reference	A synonym for array_view::value_type&.
array_view::const_reference	A synonym for array_view::value_type const&.
array_view::pointer	A synonym for array_view::value_type*.
array_view::const_pointer	A synonym for array_view::value_type const*.
array_view::iterator	A synonym for an implementation-defined array iterator of array_view::value_type.
array_view::const_iterator	A synonym for an implementation-defined array iterator of array_view::value_type const.
array_view::reverse_iterator	A synonym for std::reverse_iterator<array_view::iterator>.
array_view::const_reverse_iterator	A synonym for std::reverse_iterator<array_view::const_iterator>.

Constructors

Constructor	Description
array_view::array_view constructor	Initializes a new instance of the array_view struct as a view over (and not a copy of) the input data.

Member functions

Function	Description
array_view::at function	Returns a reference to the element at the specified position within the array_view object.
array_view::back function	Returns a reference to the last element in the array_view object.
array_view::begin function	Returns an iterator to the first element in the array_view object.
array_view::cbegin function	Returns a const iterator to the first element in the array_view object.
array_view::cend function	Returns a const iterator to one beyond the end of (one beyond the last element in) the array_view object.
array_view::crbegin function	Returns a const reverse iterator to one beyond the end of (one beyond the last element in) the array_view object.
array_view::crend function	Returns a const reverse iterator to the first element in the array_view object.
array_view::data function	Returns a pointer to the underlying data being viewed by the array_view object.
array_view::empty function	Returns a value indicating whether the array_view object is empty (is a view on zero elements).
array_view::end function	Returns an iterator to one beyond the end of (one beyond the last element in) the array_view object.
array_view::front function	Returns a reference to the first element in the array_view object.
array_view::rbegin function	Returns a reverse iterator to one beyond the end of (one beyond the last element in) the array_view object.
array_view::rend function	Returns a reverse iterator to the first element in the array_view object.
array_view::size function	Returns the number of elements in the array_view object.

Member operators

Operator	Description
array_view::operator[] (subscript operator)	Returns a reference to the element at the specified position within the array_view object.

Free operators

Operator	Description
operator!= (inequality operator)	Returns a value indicating whether the two parameters are unequal to one another.
operator< (less-than operator)	Returns a value indicating whether the first parameter is less than the second parameter.
operator<= (less-than-or-equal-to operator)	Returns a value indicating whether the first parameter is less than or equal to the second parameter.
operator== (equality operator)	Returns a value indicating whether the two parameters are equal to one another.
operator> (greater-than operator)	Returns a value indicating whether the first parameter is greater than the second parameter.
operator>= (greater-than-or-equal-to operator)	Returns a value indicating whether the first parameter is greater than or equal to the second parameter.

Iterators

An array_view is a range, and that range is defined by the array_view::begin and array_view::end member functions, each of which returns an iterator (also see array_view::cbegin and array_view::cend). Because of this, you can enumerate the characters in an array_view object with either a range-based for statement, or with the std::for_each template function.

#include <iostream>
using namespace winrt;
...
template <typename T>
void Iterators(array_view<T> const& theArrayView)
{
    for (T& element : theArrayView)
    {
        std::wcout << element << " ";
    }

    std::for_each(theArrayView.cbegin(), theArrayView.cend(), [](T const& element) { std::wcout << element << " "; });
}

array_view::array_view constructor

Initializes a new instance of the array_view struct as a view over (and not a copy of) the input data.

Syntax

array_view() noexcept;
template <typename C, uint32_t N> array_view(C(&rawArrayValue)[N]) noexcept;
template <typename C, uint32_t N> array_view(std::array<C, N> const& arrayValue) noexcept;
template <typename C, uint32_t N> array_view(std::array<C, N>& arrayValue) noexcept;
array_view(std::initializer_list<T> initializerListValue) noexcept;
template <typename C> array_view(std::vector<C> const& vectorValue) noexcept;
template <typename C> array_view(std::vector<C>& vectorValue) noexcept;
array_view(T* first, T* last) noexcept;

Template parameters

typename C The type of the values (elements) in the input data.

uint32_t N The number of values (elements) in the input data.

Parameters

rawArrayValue A raw array value that initializes the array_view object.

arrayValue A std::array value that initializes the array_view object.

initializerListValue An initializer list value that initializes the array_view object.

vectorValue A std::vector value that initializes the array_view object.

first last Pointers to values with which to initialize the array_view object. If first equals last, then the array_view object is empty.

Example

using namespace winrt;
...
void Constructors()
{
    // array_view() noexcept
    array_view<byte const> fromDefault{};

    byte theRawArray[]{ 99, 98, 97 };

    // template <typename C, uint32_t N> array_view(C(&value)[N]) noexcept
    array_view<byte const> fromRawArray{ theRawArray };

    const std::array<byte, 3> theConstArray{ 99, 98, 97 };

    // template <typename C, uint32_t N> array_view(std::array<C, N>& value) noexcept
    array_view<byte const> fromConstArray{ theConstArray };

    std::array<byte, 3> theArray{ 99, 98, 97 };

    // template <typename C, uint32_t N> array_view(std::array<C, N> const& value) noexcept
    array_view<byte const> fromArray{ theArray };

    // array_view(std::initializer_list<T> value) noexcept
    array_view<byte const> fromInitializerList{ 99, 98, 97 };

    const std::vector<byte> theConstVector{ 99, 98, 97 };

    // template <typename C> array_view(std::vector<C> const& value) noexcept
    array_view<byte const> fromConstVector{ theConstVector };

    std::vector<byte> theVector{ 99, 98, 97 };

    // template <typename C> array_view(std::vector<C>& value) noexcept
    array_view<byte const> fromVector{ theVector };

    // array_view(T* first, T* last) noexcept
    array_view<byte const> fromRange{ theArray.data(), theArray.data() + 2 }; // just the first two elements.
}

array_view::at function

Returns a reference to the element at the specified position within the array_view object.

Syntax

T& at(uint32_t const pos);
T const& at(uint32_t const pos) const;

Parameters

pos A zero-based element position, or index.

Return value

A reference to the element at the specified position within the array_view object.

array_view::back function

Returns a reference to the last element in the array_view object.

Syntax

T const& back() const noexcept;
T& back() noexcept;

Return value

A reference to the last element in the array_view object.

array_view::begin function

Returns an iterator to the first element in the array_view object. See Iterators.

Syntax

stdext::checked_array_iterator<T const> begin() const noexcept;
stdext::checked_array_iterator<T> begin() noexcept;

Return value

An iterator to the first element in the array_view object.

array_view::cbegin function

Returns a const iterator to the first element in the array_view object. See Iterators.

Syntax

stdext::checked_array_iterator<T const> cbegin() const noexcept;

Return value

A const iterator to the first element in the array_view object.

array_view::cend function

Returns a const iterator to one beyond the end of (one beyond the last element in) the array_view object. See Iterators.

Syntax

stdext::checked_array_iterator<T const> cend() const noexcept;

Return value

A const iterator to one beyond the end of (one beyond the last element in) the array_view object.

array_view::crbegin function

Returns a const reverse iterator to one beyond the end of (one beyond the last element in) the array_view object.

Syntax

std::reverse_iterator<stdext::checked_array_iterator<T const>> crbegin() const noexcept;

Return value

A const reverse iterator to one beyond the end of (one beyond the last element in) the array_view object.

array_view::crend function

Returns a const reverse iterator to the first element in the array_view object.

Syntax

std::reverse_iterator<stdext::checked_array_iterator<T const>> crend() const noexcept;

Return value

A const reverse iterator to the first element in the array_view object.

array_view::data function

Returns a pointer to the underlying data being viewed by the array_view object.

Syntax

T const* data() const noexcept;
T* data() noexcept;

Return value

A pointer to the underlying data being viewed by the array_view object.

array_view::empty function

Returns a value indicating whether the array_view object is empty (is a view on zero elements).

Syntax

bool empty() const noexcept;

Return value

true if the array_view object is empty (is a view on zero elements), otherwise false.

array_view::end function

Returns an iterator to one beyond the end of (one beyond the last element in) the array_view object. See Iterators.

Syntax

stdext::checked_array_iterator<T const> end() const noexcept;
stdext::checked_array_iterator<T> end() noexcept;

Return value

An iterator to one beyond the end of (one beyond the last element in) the array_view object.

array_view::front function

Returns a reference to the first element in the array_view object.

Syntax

T const& front() const noexcept;
T& front() noexcept;

Return value

A reference to the first element in the array_view object.

array_view::operator[] (subscript operator)

Returns a reference to the element at the specified position within the array_view object.

Syntax

T const& operator[](uint32_t const pos) const noexcept;
T& operator[](uint32_t const pos) noexcept;

Parameters

pos A zero-based element position, or index.

Return value

A reference to the element at the specified position within the array_view object.

array_view::rbegin function

Returns a reverse iterator to one beyond the end of (one beyond the last element in) the array_view object.

Syntax

std::reverse_iterator<stdext::checked_array_iterator<T const>> rbegin() const noexcept;
std::reverse_iterator<stdext::checked_array_iterator<T>> rbegin() noexcept;

Return value

A reverse iterator to one beyond the end of (one beyond the last element in) the array_view object.

array_view::rend function

Returns a reverse iterator to the first element in the array_view object.

Syntax

std::reverse_iterator<stdext::checked_array_iterator<T const>> rend() const noexcept;
std::reverse_iterator<stdext::checked_array_iterator<T>> rend() noexcept;

Return value

A reverse iterator to the first element in the array_view object.

array_view::size function

Returns the number of elements in the array_view object.

Syntax

uint32_t size() const noexcept;

Return value

A uint32_t containing the number of elements in the array_view object.

operator!= (inequality operator)

Returns a value indicating whether the two parameters are unequal to one another.

Syntax

template <typename T> bool operator!=(winrt::array_view<T> const& left, winrt::array_view<T> const& right) noexcept;

Parameters

left right An array_view value to compare with the other parameter.

Return value

true if the two parameters are unequal to one another, otherwise false.

operator< (less-than operator)

Returns a value indicating whether the first parameter is less than the second parameter.

Syntax

template <typename T> bool operator<(winrt::array_view<T> const& left, winrt::array_view<T> const& right) noexcept;

Parameters

left right An array_view value to compare with the other parameter.

Return value

true if the first parameter is less than the second parameter, otherwise false.

operator<= (less-than-or-equal-to operator)

Returns a value indicating whether the first parameter is less than or equal to the second parameter.

Syntax

template <typename T> bool operator<=(winrt::array_view<T> const& left, winrt::array_view<T> const& right) noexcept;

Parameters

left right An array_view value to compare with the other parameter.

Return value

true if the first parameter is less than or equal to the second parameter, otherwise false.

operator== (equality operator)

Returns a value indicating whether the two parameters are equal to one another.

Syntax

template <typename T> bool operator==(winrt::array_view<T> const& left, winrt::array_view<T> const& right) noexcept;

Parameters

left right An array_view value to compare with the other parameter.

Return value

true if the two parameters are equal to one another, otherwise false.

operator> (greater-than operator)

Returns a value indicating whether the first parameter is greater than the second parameter.

Syntax

template <typename T> bool operator>(winrt::array_view<T> const& left, winrt::array_view<T> const& right) noexcept;

Parameters

left right An array_view value to compare with the other parameter.

Return value

true if the first parameter is greater than the second parameter, otherwise false.

operator>= (greater-than-or-equal-to operator)

Returns a value indicating whether the first parameter is greater than or equal to the second parameter.

Syntax

template <typename T> bool operator>=(winrt::array_view<T> const& left, winrt::array_view<T> const& right) noexcept;

Parameters

left right An array_view value to compare with the other parameter.

Return value

true if the first parameter is greater than or equal to the second parameter, otherwise false.

See also

• winrt namespace