std::basic_string_view<CharT,Traits>::size, std::basic_string_view<CharT,Traits>::length

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

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 Element access basic_string_view::at basic_string_view::operator[] basic_string_view::front basic_string_view::back basic_string_view::data Capacity basic_string_view::sizebasic_string_view::length basic_string_view::max_size basic_string_view::empty Modifiers basic_string_view::remove_prefix basic_string_view::remove_suffix basic_string_view::swap

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 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)

 

constexpr size_type size() const noexcept;		(since C++17)
constexpr size_type length() const noexcept;		(since C++17)

Returns the number of CharT elements in the view, i.e. std::distance(begin(), end()).

Parameters

(none)

Return value

The number of CharT elements in the view.

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

empty (C++17)	checks whether the view is empty (public member function)
max_size (C++17)	returns the maximum number of characters (public member function)
sizelength	returns the number of characters (public member function of std::basic_string<CharT,Traits,Allocator>)