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

constexpr basic_string_view substr( size_type pos = 0,
                                    size_type count = npos ) const;

Gibt eine Ansicht des Teilstrings [pos, pos + rlen) zurück, wobei rlen das kleinere von count und size() - pos ist.

Parameter

Rückgabewert

Ansicht des Teilstrings [ pos , pos + rlen ) .

Exceptions

std::out_of_range wenn pos > size ( ) .

Komplexität

Konstante.

Beispiel

#include <cstddef>
#include <iostream>
#include <stdexcept>
#include <string_view>
int main()
{
    typedef std::size_t count_t, pos_t;
    constexpr std::string_view data{"ABCDEF"};
    std::cout << data.substr() << '\n'; // ABCDEF, d.h. data[0, 5] also [0, 6)
    std::cout << data.substr(pos_t(1)) << '\n'; // BCDEF, d.h. [1, 6)
    std::cout << data.substr(pos_t(2), count_t(3)) << '\n'; // CDE, d.h. [2, 2 + 3)
    std::cout << data.substr(pos_t(4), count_t(42)) << '\n'; // EF, d.h. [4, 6)
    try
    {
        [[maybe_unused]]
        auto sub = data.substr(pos_t(666), count_t(1)); // wirft Exception: pos > size()
    {
    catch (std::out_of_range const& ex)
    {
        std::cout << ex.what() << '\n';
    }
}

ABCDEF
BCDEF
CDE
EF
basic_string_view::substr: __pos (which is 666) > __size (which is 6)

Siehe auch