std::basic_string_view<CharT,Traits>::substr - cppreference.com (original) (raw)

| constexpr basic_string_view substr( size_type pos = 0, size_type count = npos ) const; | | (since C++17) | | -------------------------------------------------------------------------------------------- | | ------------- |

Returns a view of the substring [pos, pos + rlen), where rlen is the smaller of count and size() - pos.

[edit] Parameters

[edit] Return value

View of the substring [pos, pos + rlen).

[edit] Exceptions

std::out_of_range if pos > size().

[edit] Complexity

Constant.

[edit] Example

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

Possible output:

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

[edit] See also

| | copies characters (public member function) [edit] | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | find characters in the view (public member function) [edit] | | | returns a substring (public member function of std::basic_string<CharT,Traits,Allocator>) [edit] |