NAME¶

std::span::begin,std::span::cbegin - std::span::begin,std::span::cbegin

Synopsis¶

constexpr iterator begin() const noexcept; (1) (since C++20)
constexpr const_iterator cbegin() const noexcept; (2) (since C++23)

Returns an iterator to the first element of the span.

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

range-begin-end.svg

Parameters¶

(none)

Return value¶

Iterator to the first element.

Complexity¶

Constant.

Example¶

// Run this code

#include <iostream>
#include <span>

void print(std::span<const int> array)
{
std::cout << "array = ";
for (auto it = array.begin(); it != array.end(); ++it)
std::cout << *it << ' ';
std::cout << '\n';
}

void set_first_element(std::span<int> sp, int new_value)
{
if (!sp.empty())
{
std::cout << "old *begin = " << *sp.begin() << '\n';
*sp.begin() = new_value;
std::cout << "new *begin = " << *sp.begin() << '\n';
}
}

int main()
{
int array[]{1, 3, 4, 5};
print(array);
set_first_element(array, 2);
print(array);
}

Output:¶

array = 1 3 4 5
old *begin = 1
new *begin = 2
array = 2 3 4 5

See also¶

end returns an iterator to the end
cend (public member function)
(C++23)
begin
cbegin returns an iterator to the beginning of a container or array
(C++11) (function template)
(C++14)