C++26 for C++14 Developers: STL-Preview Author Tony Lee Reply-To cosgenio@gmail.com 1. Introduction Since the introduction of modern C++ in 2011, the language has seen rely on C++14 or C++17, with minimal adoption of C++20 or later１. This paper introduces stl-preview２, a library that backports most of the latest STL features (including those from C++26) to C++14 (but expected. It has been tested on various compilers including GCC, Clang, MSVC, Emscripten, and NDK with C++14 or later. Besides the extensive implementations, stl-preview is compatible with the existing STL

= e; } return std::pair{a, b}; }); return a * a + b * b; } C++20 Concepts C++14 Function Deduced Return Type C++14 Generic Lambdas C++17 Structured Bindings C++17 CTADauto solution2(auto }); return std::accumulate(std::begin(v), std::begin(v) + 2, 0, std::plus{}); }C++20 Concepts C++14 Function Deduced Return Type C++17 CTAD C++20 Ranges auto solution3(auto v) { using namespace (map fib (enumerate-interval 0 n)))))C++20 Ranges C++20 Concepts C++14 Generic Lambdas C++14 Function Deduced Return Type C++14 Generic Lambdas C++20 Concepts1. Generate odd numbers 2. Group

josuttis | eckstei err 1下rcommunication C++14: Named Generic Lambdas /idefine a generic lambda object: auto twice = [] (const autog x) { return Cr+ Lambdas Generic Lambdas (since C++14) "Generic Lambdas =- Call arguments may have a generic type ， auto, const autog,… =- Not possible Cr+ Lambdas C++14: Generic Lambdas *。Lambdas for generic parameter types =- Using auto =- Defines function template

. . . . . . . . . . 83 6 序言 序言 引言 C++ 是一个用户群体相当大的语言。从 C++98 的出现到 C++11 的正式定稿经历了长达十年多之 久的积累。C++14/17 则是作为对 C++11 的重要补充和优化，C++20 则将这门语言领进了现代化的大 门，所有这些新标准中扩充的特性，给 C++ 这门语言注入了新的活力。那些还在坚持使用传统 C++ （本书把 return n == 1 || n == 2 ? 1 : fibonacci(n-1)+fibonacci(n-2); } 14 2.2 变量及其初始化 第 2 章语言可用性的强化 从 C++14 开始，constexpr 函数可以在内部使用局部变量、循环和分支等简单语句，例如下面的 代码在 C++11 的标准下是不能够通过编译的： constexpr int fibonacci(const template auto add2(T x, U y) -> decltype(x+y){ return x + y; } 令人欣慰的是从 C++14 开始是可以直接让普通函数具备返回值推导，因此下面的写法变得合法： template auto add3(T x, U y){ return x

return ++x; }; 20Lambda Expressions ● Capture Clause ○ C++11 ■ capture by value or reference ○ C++14 ■ generalized capture was added 21Lambda Expressions ● Capture Clause ○ generalized capture ■ evaluated 22Lambda Expressions ● Capture Clause ○ C++11 ■ [this] ■ captures this pointer by value ○ C++14 ■ [self = *this] ■ capture *this object by value, initializes a new variable ○ C++17 ■ [*this] declarations for the arguments passed to the closure ■ default parameters were not permitted ○ C++14 ■ parameters can have a data type of auto (generic lambda) ■ default parameters are supported auto

From the advent of C++98 to the official finalization of C++11, it has continued to stay relevant. C++14/17 is an important complement and optimization for C++11, and C++20 brings this language to the door fibonacci(const int n) { return n == 1 || n == 2 ? 1 : fibonacci(n-1) + fibonacci(n-2); } Starting with C++14, the constexpr function can use simple statements such as local variables, loops, and branches internally typename U> auto add2(T x, U y) -> decltype(x+y){ return x + y; } The good news is that from C++14 it is possible to directly derive the return value of a normal function, so the following way becomes

Example features C++20 Concepts Non-type template parameters C++17 Fold expressions constexpr if C++14 More permissive constexpr auto return type C++11 Primitive constexpr Variadic templates static_assert Example features C++20 Concepts Non-type template parameters C++17 Fold expressions constexpr if C++14 More permissive constexpr auto return type C++11 Primitive constexpr Variadic templates static_assert Example features C++20 Concepts Non-type template parameters C++17 Fold expressions constexpr if C++14 More permissive constexpr auto return type C++11 Primitive constexpr Variadic templates static_assert

standards Coding Standard C++ Versions Autosar C++14 Misra C++03 (working to C++17) High Integrity CPP C++11 JSF C++03 C++ CG C++11/14/17/20/latest CERT C++ C++14 Pedigree Coding Standard Number of Rules waiting Fixed gaps in memory model , Improved atomic flags, Repair memory model C++11: lambda C++14: generic lambda C++17: , progress guarantees, TOE, execution policies C++20: atomic_ref Future even miss a few C++17 features • MISRA parallel will also be in stages • C++11 atomics, async .mm • C++14 shared lock • C++17 parallel algo, futures, (still need more deep dive) unseq, • C++20 latches barriers

正确（推荐） 字符串的连接（ + 运算符） • 错误： • 正确： C++14 新特性：自定义字面量后缀 • 不少同学就觉得这样好麻烦，其他语言都是直接 “ hello” 就是字符串类 型， C++ 还得套一层壳 string(“hello”) 才能变成安全封装的类型，才能用他 的成员函数。 • 因此， C++14 引入了一项缓解“键盘压力”的新特性： • 写 “ hello”_s 就相当于写 字符串没要求一定是 ‘ \0’ 结尾，字符串里是可以包含 ‘ \0’ 的。 C++14 新特性：自定义字面量后缀 • 如果你 using namespace std; 其实标准库已经自动帮你定义好了 “” s 后缀。 • 这里 “ hello”s 就等价于原本繁琐的 string(“hello”) 了。 C++14 新特性：自定义字面量后缀 • 如果你觉得 using namespace std; u32string U" 字符 " 4 UTF-32 其中后面三个是不随系统而改变的（ C++ 标准委员会定义） 前面三个是随系统而改变的（ Linux 和 Windows 自己定义）。 和 C++14 自定义常量后缀的联动： “ 字符” s 会得到 string 。 L“ 字符” s 会得到 wstring 。 “ 字符” sv 会得到 string_view 。 L“ 字符” sv 会得到 wstring_view

projects 2016 - C++Now “Why and How to Add Scripting” 2011-2017 - Ported ChaiScript from Boost  C++11  C++14  C++17 7 . 6Copyright Jason Turner @le�icus emptycrate.com/idocpp Why This Talk? 2010-2023 - projects 2016 - C++Now “Why and How to Add Scripting” 2011-2017 - Ported ChaiScript from Boost  C++11  C++14  C++17 2019-2023 - Pondered making a newer constexpr friendly embedded scripting engine 7 . 6Copyright projects 2016 - C++Now “Why and How to Add Scripting” 2011-2017 - Ported ChaiScript from Boost  C++11  C++14  C++17 2019-2023 - Pondered making a newer constexpr friendly embedded scripting engine 2023 - Created