std::basic_string<CharT,Traits,Allocator>::subview

constexpr std::basic_string_view<CharT, Traits> subview( size_type pos = 0,
                                                         size_type count = npos ) const;

(since C++26)

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

Equivalent to return std::basic_string_view<CharT, Traits>(*this).subview(pos, count);.

Parameters

pos	-	position of the first character to include
count	-	length of the sub-view

Return value

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

Exceptions

std::out_of_range if pos > size().

Complexity

Constant.

Notes

Feature-test macro	Value	Std	Feature
`__cpp_lib_string_subview`	`202506L`	(C++26)	`std::basic_string::subview`, `std::basic_string_view::subview`

Example

#include <cassert>
#include <iostream>
#include <string>
#include <string_view>

int main()
{
    const std::string s{"Life is life!"};
    assert(s.subview(5) == "is life!");
    assert(s.subview(5, 13) == "is life!");
    assert(s.subview(5, 2) == "is");

    try
    {
        // pos is out of bounds, throws
        const auto pos{s.length() + 13};
        [[maybe_unused]] auto x_x{s.subview(pos)};
    }
    catch (const std::out_of_range& ex)
    {
        std::cout << "Exception: " << ex.what() << '\n';
    }
}

Possible output:

Exception: basic_string_view::substr: __pos (which is 26) > __size (which is 13)

substr	returns a substring (public member function)
subview (C++26)	returns a sub-view (public member function of `std::basic_string_view<CharT,Traits>`)