From cppreference.com
constexprboolempty()constnoexcept;(since C++17)Checks if the view has no characters, i.e., whether
==0.
Return value
true if the view is empty, false otherwise.
Complexity
Constant.
Example
Run this code
#include<iostream>#include<string_view>// Print a string surrounded by single quotes, its// length and whether it is considered empty.voidcheck_string(std::string_viewref){std::cout<<std::boolalpha<<"'"<<ref<<"' has "<<ref.size()<<" character(s); emptiness: "<<ref.empty()<<'\n';}intmain(intargc,char**argv){// An empty stringcheck_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 See also
returns the number of characters
(public member function)
returns the maximum number of characters
(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)
checks whether the string is empty
(public member function of std::basic_string<CharT,Traits,Allocator>)