std::basic_string_view
的推导指引
来自cppreference.com
< cpp | string | basic string view
定义于头文件 <string_view>
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template<class It, class End> basic_string_view(It, End) -> basic_string_view<std::iter_value_t<It>>; |
(1) | (C++20 起) |
template<class R> basic_string_view(R&&) -> basic_string_view<ranges::range_value_t<R>>; |
(2) | (C++23 起) |
为 std::basic_string_view 提供这些推导指引。
示例
运行此代码
#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()); // 推导: 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()); // 推导: 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()); // 推导: CharT -> long static_assert(std::is_same_v<decltype(s3)::value_type, long>); for (const auto e : s3) { std::cout << static_cast<char>(e); } }
输出:
nucleons: protons neutrons