std::span<T,Extent>::begin

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

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Containers library

Iterators library

Ranges library (C++20)

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Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

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forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Iterator invalidation

Member function table

Non-member function table

 

std::span

Member functions

span::span

span::operator=

Element access

span::front

span::back

span::operator[]

span::data

Iterators

span::begin

span::end

span::rbegin

span::rend

Observers

span::empty

span::size

span::size_bytes

Subviews

span::first

span::last

span::subspan

Non-member functions

as_bytesas_writable_bytes

Non-member constant

dynamic_extent

Deduction guides

 

constexpr iterator begin() const noexcept;

Returns an iterator to the first element of the span.

If the span is empty, the returned iterator will be equal to end().

Parameters

(none)

Return value

Iterator to the first element.

Complexity

Constant.

Example

Run this code

#include <span>
#include <iostream>
 
void print(std::span<const int> sp)
{
    for(auto it = sp.begin(); it != sp.end(); ++it) {
        std::cout << *it << ' ';
    }
    std::cout << '\n';
}
 
void transmogrify(std::span<int> sp)
{
    if (!sp.empty()) {
        std::cout << *sp.begin() << '\n';
        *sp.begin() = 2;
    }
}
 
int main()
{
    int array[] { 1, 3, 4, 5 };
    print(array);
    transmogrify(array);
    print(array);
}

Output:

1 3 4 5 
1
2 3 4 5

See also

end (C++20)	returns an iterator to the end (public member function)
begincbegin (C++11)(C++14)	returns an iterator to the beginning of a container or array (function template)