Method begin

3rd/asio-1.24.0/include/asio/buffer.hpp:365–368

Get a random-access iterator to the first element.

  /// Get a random-access iterator to the first element.
  const_iterator begin() const ASIO_NOEXCEPT
  {
    return &buf_;
  }

  /// Get a random-access iterator for one past the last element.
  const_iterator end() const ASIO_NOEXCEPT