NAME¶

std::mdspan::operator[] - std::mdspan::operator[]

Synopsis¶

template< class... OtherIndexTypes >
constexpr reference operator[]( OtherIndexTypes... indices ) (1) (since C++23)
const;
template< class OtherIndexType >

constexpr reference operator[] (2) (since C++23)

( std::span<OtherIndexType, rank()> indices ) const;
template< class OtherIndexType >

constexpr reference operator[] (3) (since C++23)

( const std::array<OtherIndexType, rank()>& indices ) const;

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[](extents_type::index-cast(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.

Example¶

This section is incomplete
Reason: no example

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3974 C++23 overloads (2,3) did not apply applies
extents_type::index-cast

See also¶

This section is incomplete

Categories:¶

* Todo no example
* Todo without reason