std::basic_string<CharT,Traits,Allocator>::empty
bool empty() const; |
(until C++11) | |
bool empty() const noexcept; |
(since C++11) (until C++20) |
|
[[nodiscard]] constexpr bool empty() const noexcept; |
(since C++20) |
Checks if the string has no characters, i.e. whether begin() == end().
Parameters
(none).
Return value
true if the string is empty, false otherwise.
Complexity
Constant.
Example
#include <iostream>
#include <string>
int main()
{
std::string s;
std::boolalpha(std::cout);
std::cout << "s.empty():" << s.empty() << "\t s:'" << s << "'\n";
s = "Exemplar";
std::cout << "s.empty():" << s.empty() << "\t s:'" << s << "'\n";
s = "";
std::cout << "s.empty():" << s.empty() << "\t s:'" << s << "'\n";
}
Output:
s.empty():true s:'' s.empty():false s:'Exemplar' s.empty():true s:''
See also
| returns the number of characters (public member function) |
|
| returns the maximum number of characters (public member function) |
|
| returns the number of characters that can be held in currently allocated storage (public member function) |
|
|
(C++17)(C++20)
|
returns the size of a container or array (function template) |
|
(C++17)
|
checks whether the container is empty (function template) |
|
(C++17)
|
checks whether the view is empty (public member function of std::basic_string_view<CharT,Traits>) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/string/basic_string/empty
