NAME

deductionguidesforstd::basic_string_view - deductionguidesforstd::basic_string_view

Synopsis

Defined in header <string_view>
template<class It, class End>
basic_string_view(It, End) -> (1) (since C++20)
basic_string_view<std::iter_value_t<It>>;
template<class R>
basic_string_view(R&&) -> (2) (since C++23)
basic_string_view<ranges::range_value_t<R>>;

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

// Run this code

#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