std::span::front(3)

NAME
std::span::front - std::span::front

Synopsis
   constexpr reference front() const; (since C++20)
   Returns a reference to the first element in the span.
   Calling front on an empty span results in undefined behavior.

Parameters
   (none)

Return value
   A reference to the first element.

Complexity
   Constant.

Notes
   For a span c, the expression c.front() is equivalent to *c.begin().

Example
// Run this code
 #include <iostream>
 #include <span>
 void print(std::span<const int> const data)
 {
     for (auto offset{0U}; offset != data.size(); ++offset)
         std::cout << data.subspan(offset).front() << ' ';
     std::cout << '\n';
 }
 int main()
 {
     constexpr int data[]{0, 1, 2, 3, 4, 5, 6};
     print({data, 4});
 }

Output:
 0 1 2 3

See also
   back access the last element
        (public member function)