std::basic_string_view<CharT,Traits>::empty - cppreference.com (original) (raw)

| constexpr bool empty() const noexcept; | | (since C++17) | | -------------------------------------- | | ------------- |

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

[edit] Parameters

(none)

[edit] Return value

true if the view is empty, false otherwise.

[edit] Complexity

Constant.

[edit] Example

#include #include   // Print a string surrounded by single quotes, its // length and whether it is considered empty. void check_string(std::string_view ref) { 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

[edit] See also

| | returns the number of characters (public member function) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | returns the maximum number of characters (public member function) [edit] | | | returns the size of a container or array (function template) [edit] | | | checks whether the container is empty (function template) [edit] | | | checks whether the string is empty (public member function of std::basic_string<CharT,Traits,Allocator>) [edit] |