deduction guides for std::basic_string_view
Defined in header <string_view> |
||
|---|---|---|
template<class It, class End> basic_string_view(It, End) -> basic_string_view<std::iter_value_t<It>>; |
(1) | (since C++20) |
template<class R> basic_string_view(R&&) -> basic_string_view<ranges::range_value_t<R>>; |
(2) | (since C++23) |
These deduction guides are provided for std::basic_string_view.
1) This deduction guide allow the character type to be deduced from the iterator-sentinel pair. This overload participates in overload resolution only if
It satisfies
contiguous_iterator and
End satisfies
sized_sentinel_for for
It.
2) This deduction guide allow the character type to be deduced from the range. This overload participates in overload resolution only if
R satisfies
contiguous_range.
Example
#include <array>
#include <iostream>
#include <string_view>
int main()
{
std::array a1 {'n', 'u', 'c', 'l', 'e', 'o', 'n', 's', ':', '\n'};
std::basic_string_view s1(a1.cbegin(), a1.cend()); // deduction: CharT -> char
static_assert(std::is_same_v<decltype(s1)::value_type, char>);
std::cout << s1;
std::array a2 {L'p', L'r', L'o', L't', L'o', L'n', L's', L'\n'};
std::basic_string_view s2(a2.cbegin(), a2.cend()); // deduction: CharT -> wchar_t
static_assert(std::is_same_v<decltype(s2)::value_type, wchar_t>);
std::wcout << s2;
std::array<long, 9> a3 {'n', 'e', 'u', 't', 'r', 'o', 'n', 's', '\n'};
std::basic_string_view s3(a3.cbegin(), a3.cend()); // deduction: CharT -> long
static_assert(std::is_same_v<decltype(s3)::value_type, long>);
for (const auto e : s3) { std::cout << static_cast<char>(e); }
}
Output:
nucleons: protons neutrons
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https://en.cppreference.com/w/cpp/string/basic_string_view/deduction_guides
