std::basic_string_view<CharT,Traits>::empty (3) - Linux Manuals

std::basic_string_view<CharT,Traits>::empty: std::basic_string_view<CharT,Traits>::empty

NAME

std::basic_string_view<CharT,Traits>::empty - std::basic_string_view<CharT,Traits>::empty

Synopsis

constexpr bool empty() const noexcept; (since C++17)
                                                      (until C++20)
[[nodiscard]] constexpr bool empty() const noexcept; (since C++20)

Checks if the view has no characters, i.e. whether size() == 0.

Parameters

(none)

Return value

true if the view is empty, false otherwise

Complexity

Constant.

Example

// Run this code

  #include <string_view>
  #include <iostream>

  void check_string(std::string_view ref)
  {
          // Print a string surrounded by single quotes, its length
          // and whether it is considered empty.
          std::cout << std::boolalpha
                    << "'" << ref << "' has " << ref.size()
                    << " character(s); emptiness: " << ref.empty() << '\n';
  }

  int main(int argc, char **argv)
  {
          // An empty string
          check_string("");

          // Almost always not empty: argv[0]
          if (argc > 0)
                  check_string(argv[0]);
  }

Possible output:

  '' has 0 character(s); emptiness: true
  './a.out' has 7 character(s); emptiness: false