Defined in header <span> | ||
|---|---|---|
template<
class T,
std::ptrdiff_t Extent = std::dynamic_extent
> class span;
| (since C++20) |
The class template span describes an object that can refer to a contiguous sequence of objects with the first element of the sequence at position zero. A span can either have a static extent, in which case the number of elements in the sequence is known and encoded in the type, or a dynamic extent.
A typical implementation holds only two members: a pointer to T and a size.
| T | - | element type; must be a complete type that is not an abstract class type |
| Extent | - | the number of elements in the sequence, or std::dynamic_extent if dynamic; the program is ill-formed if Extent is negative and is not std::dynamic_extent |
| Member type | Definition |
|---|---|
element_type | T |
value_type | std::remove_cv_t<T> |
index_type | std::ptrdiff_t |
difference_type | std::ptrdiff_t |
pointer | T* |
reference | T& |
iterator | implementation-defined RandomAccessIterator, ConstexprIterator, and ContiguousIterator whose value_type is value_type |
const_iterator | implementation-defined constant RandomAccessIterator, ConstexprIterator, and ContiguousIterator whose value_type is value_type |
reverse_iterator | std::reverse_iterator<iterator> |
const_reverse_iterator | std::reverse_iterator<const_iterator> |
Note: iterator is a mutable iterator if T is not const-qualified.
All requirements on the iterator types of a Container applies to the iterator and const_iterator types of span as well.
static constexpr std::ptrdiff_t extent = Extent; |
constructs a span (public member function) |
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assigns a span (public member function) |
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Iterators |
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| returns an iterator to the beginning of the sequence (public member function) |
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| returns an iterator to the end of the sequence (public member function) |
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| returns a reverse iterator to the beginning of the sequence (public member function) |
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| returns a reverse iterator to the end of the sequence (public member function) |
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Element access |
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| accesses an element of the sequence (public member function) |
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| returns a pointer to the beginning of the sequence of elements (public member function) |
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Observers |
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| returns the number of elements in the sequence (public member function) |
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| returns the size of the sequence in bytes (public member function) |
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| checks if the sequence is empty (public member function) |
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Subviews |
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| obtains a subspan consisting of the first N elements of the sequence (public member function) |
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| obtains a subspan consisting of the last N elements of the sequence (public member function) |
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| obtains a subspan (public member function) |
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compares the elements of two spans (function template) |
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converts a span into a view of its underlying bytes (function template) |
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(C++20) | a constant of type ptrdiff_t (constant) |
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