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

 

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Strings library

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basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string_view

Member functions basic_string_view::basic_string_view    basic_string_view::operator= Iterators basic_string_view::beginbasic_string_view::cbegin basic_string_view::endbasic_string_view::cend basic_string_view::rbeginbasic_string_view::crbegin basic_string_view::rendbasic_string_view::crend Capacity basic_string_view::sizebasic_string_view::length basic_string_view::max_size basic_string_view::empty Operations basic_string_view::copy basic_string_view::substr basic_string_view::compare basic_string_view::starts_with (C++20) basic_string_view::ends_with (C++20) basic_string_view::contains (C++23) basic_string_view::find basic_string_view::rfind basic_string_view::find_first_of basic_string_view::find_last_of basic_string_view::find_first_not_of basic_string_view::find_last_not_of

Element access basic_string_view::at basic_string_view::operator[] basic_string_view::front basic_string_view::back basic_string_view::data Modifiers basic_string_view::remove_prefix basic_string_view::remove_suffix basic_string_view::swap Constants basic_string_view::npos Non-member functions operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) operator<< operator""sv Helper classes hash<std::string_view>hash<std::wstring_view>hash<std::u8string_view>hash<std::u16string_view>hash<std::u32string_view> (C++20) Deduction guides(C++20)

 

constexprbool empty()constnoexcept;		(since C++17)

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 <iostream>#include <string_view>   // 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

See also

sizelength	returns the number of characters (public member function)
max_size	returns the maximum number of characters (public member function)
sizessize (C++17)(C++20)	returns the size of a container or array (function template)
empty (C++17)	checks whether the container is empty (function template)
empty	checks whether the string is empty (public member function of std::basic_string<CharT,Traits,Allocator>)