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std::mdspan<T,Extents,LayoutPolicy,AccessorPolicy>::operator[]

template< class... OtherIndexTypes >
constexpr reference operator[]( OtherIndexTypes... indices ) const;

(1)

(since C++23)

template< class OtherIndexType >
constexpr reference operator[]( std::span<OtherIndexType, rank()> indices ) const;

(2)

(since C++23)

template< class OtherIndexType >
constexpr reference operator[]( const std::array<OtherIndexType, rank()>& indices ) const;

(3)

(since C++23)

Returns a reference to the indices^th element of the mdspan.

1) Equivalent to return acc_.access(ptr_, map_(static_cast<index_type>(std::move(indices))...));.

This overload participates in overload resolution only if:

(std::is_convertible_v<OtherIndexTypes, index_type> && ...) is true,
(std::is_nothrow_constructible_v<index_type, OtherIndexTypes> && ...) is true, and
sizeof...(OtherIndexTypes) == rank() is true.

Let I be extents_type::index-cast(std::move(indices)). Then the behavior is undefined if I is not a multidimensional index in extents(), i.e., map_(I) < map_.required_span_size() is false.

2,3) Let P be a parameter pack such that std::is_same_v<make_index_sequence<rank()>, index_sequence<P...>> is true, then the operator is equivalent to return operator[](std::as_const(indices[P])...);.

This overload participates in overload resolution only if:

std::is_convertible_v<const OtherIndexType&, index_type> is true, and
std::is_nothrow_constructible_v<index_type, const OtherIndexType&> is true.

Parameters

indices

the indices of the element to access

Return value

A reference to the element.

W3cubDocs

std::mdspan<T,Extents,LayoutPolicy,AccessorPolicy>::operator[]

Parameters

Return value

Example

See also