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

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

#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

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

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