std::span<T,Extent>::begin, std::span<T,Extent>::cbegin
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Containers library
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Tables
std::span
(C++26)
span::beginspan::cbegin
(C++23)
(C++23)
(C++23)
(C++23)
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 *this.
If *this is empty, the returned iterator will be equal to end().
Contents
[edit] Return value
Iterator to the first element.
[edit] Complexity
Constant.
[edit] 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
[edit] See also
(C++11)(C++14)
(function template) [edit]