c++ - C ++ 17中有哪些新功能？(What are the new features in C++17?)

Question

C++17 is now feature complete, so unlikely to experience large changes. (C ++ 17现在功能齐全，因此不太可能经历大的变化。) Hundreds of proposals were put forward for C++17. (为C ++ 17提出了数百个提案。)

Which of those features were added to C++ in C++17? (在C ++ 17中，哪些特性被添加到C ++中？)

When using a C++ compiler that supports "C++1z", which of those features are going to be available when the compiler updates to C++17? (当使用支持“C ++ 1z”的C ++编译器时，当编译器更新到C ++ 17时，哪些功能可用？)

  ask by Yakk - Adam Nevraumont translate from so

Answer 1

Language features: (语言特色：)

Templates and Generic Code (模板和通用代码)

• Template argument deduction for class templates (类模板的模板参数推导)

  • Like how functions deduce template arguments, now constructors can deduce the template arguments of the class (就像函数如何推导模板参数一样，现在构造函数可以推导出类的模板参数)
  • http://wg21.link/p0433r2 http://wg21.link/p0620r0 http://wg21.link/p0512r0 (http://wg21.link/p0433r2 http://wg21.link/p0620r0 http://wg21.link/p0512r0)

• template <auto>

  • Represents a value of any (non-type template argument) type. (表示任何（非类型模板参数）类型的值。)

• Non-type template arguments fixes (非类型模板参数修复)

• template<template<class...>typename bob> struct foo {}

• ( Folding + ... + expressions ) and Revisions (（折叠+ ... +表达式）和修订版)

• auto x{8}; is an int (是一个int)

• modernizing using with ... and lists (using ...和列表进行现代化改造)

Lambda (LAMBDA)

• constexpr lambdas (constexpr lambdas)

  • Lambdas are implicitly constexpr if they qualify (如果Lambdas符合条件，他们就会隐瞒constexpr)

• Capturing *this in lambdas (在lambdas中捕获*this)

  • [*this]{ std::cout << could << " be " << useful << '\n'; }

Attributes (属性)

• [[fallthrough]] , [[nodiscard]] , [[maybe_unused]] attributes ([[fallthrough]] ， [[nodiscard]] ， [[maybe_unused]]属性)

• [[attributes]] on namespace s and enum { erator[[s]] } (namespace s和enum { erator[[s]] }上的[[attributes]])

• using in attributes to avoid having to repeat an attribute namespace. (在属性中using以避免重复属性命名空间。)

• Compilers are now required to ignore non-standard attributes they don't recognize . (编译器现在需要忽略它们无法识别的非标准属性 。)

  • The C++14 wording allowed compilers to reject unknown scoped attributes. (C ++ 14的措辞允许编译器拒绝未知的范围属性。)

Syntax cleanup (语法清理)

• Inline variables (内联变量)

  • Like inline functions (像内联函数)
  • Compiler picks where the instance is instantiated (编译器选择实例实例化的位置)
  • Deprecate static constexpr redeclaration , now implicitly inline. (弃用静态constexpr重新声明 ，现在隐式内联。)

• namespace A::B

• Simple static_assert(expression); (简单的static_assert(expression);) with no string (没有字符串)

• no throw unless throw() , and throw() is noexcept(true) . (没有throw ，除非throw()和throw()是noexcept(true) 。)

Cleaner multi-return and flow control (更清洁的多回程和流量控制)

• Structured bindings (结构化绑定)

  • Basically, first-class std::tie with auto (基本上，一流的std::tie与auto)
  • Example: (例：)
    • const auto [it, inserted] = map.insert( {"foo", bar} ); <