std::span

 

C++

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Headers

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Named requirements

Language support library

Concepts library (C++20)

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Utilities library

Strings library

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Regular expressions library (C++11)

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Technical Specifications

 

Containers library

array (C++11)

vector

deque

forward_list (C++11)

list

set

multiset

map

multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

queue

priority_queue

span (C++20)

 

std::span

Member functions

span::span

span::operator=

Element access

span::operator[]span::operator()

span::data

Iterators

span::beginspan::cbegin

span::endspan::cend

span::rbeginspan::crbegin

span::rendspan::crend

Observers

span::empty

span::size

span::size_bytes

Subviews

span::first

span::last

span::subspan

Non-member functions

operator==operator!=operator<operator<=operator>operator>=

as_bytesas_writable_bytes

Non-member constant

dynamic_extent

Deduction guides

 

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.

Template parameters

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 types

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.

Member constant

static constexpr std::ptrdiff_t extent = Extent;

Member functions

(constructor)	constructs a span (public member function)
operator=	assigns a span (public member function)
Iterators
begincbegin	returns an iterator to the beginning of the sequence (public member function)
endcend	returns an iterator to the end of the sequence (public member function)
rbegincrbegin	returns a reverse iterator to the beginning of the sequence (public member function)
rendcrend	returns a reverse iterator to the end of the sequence (public member function)
Element access
operator[]operator()	accesses an element of the sequence (public member function)
data	returns a pointer to the beginning of the sequence of elements (public member function)
Observers
size	returns the number of elements in the sequence (public member function)
size_bytes	returns the size of the sequence in bytes (public member function)
empty	checks if the sequence is empty (public member function)
Subviews
first	obtains a subspan consisting of the first N elements of the sequence (public member function)
last	obtains a subspan consisting of the last N elements of the sequence (public member function)
subspan	obtains a subspan (public member function)

Non-member functions

operator==operator!=operator<operator<=operator>operator>=	compares the elements of two spans (function template)
as_bytesas_writable_bytes	converts a span into a view of its underlying bytes (function template)

Non-member constant

dynamic_extent (C++20)

a constant of type ptrdiff_t (constant)