<p>C 20 introduces a number of important new features, significantly improving code simplicity, security and development efficiency. The first is the module system (Modules), which replaces #include through import, defines interfaces using .cppm files to improve compilation speed and improve dependency management; the second is the range library (Ranges), which supports chain operations such as filter and transform, and simplifies container processing; the third is coroutines, which realizes the synchronous style of asynchronous programming through keywords such as co_await and co_yield; and finally, the three-way comparison operator , which can automatically deduce all comparison relationships and reduce boilerplate code. These features make the C 20 more expressive and practical in modern software development. </p> <p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175234567137654.jpg" class="lazy" alt="C tutorial covering C 20 new features"></p> <p> C 20 is an important milestone in C's development process, bringing many new features and improvements. These new features not only make the code more concise and secure, but also improve development efficiency and readability. If you are already familiar with C 17 or earlier, this article will take you to quickly learn about the most noteworthy new features in C 20. </p> <img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175234567246252.jpeg" class="lazy" alt="C tutorial covering C 20 new features"><hr> <h3 id="Modules"> Modules</h3> <p> Traditional header file mechanisms are prone to cause slow compilation and complex dependencies in large projects. C 20 introduces modules, providing a more modern way to organize code. </p> <img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175234567440922.jpeg" class="lazy" alt="C tutorial covering C 20 new features"><ul> <li> Use <code>import</code> instead of <code>#include</code> to avoid duplicate parsing of header files.</li> <li> The module defines the interface through <code>.ixx</code> or <code>.cppm</code> files to achieve clearer encapsulation.</li> <li> The compiler can cache modules to improve compilation speed.</li> </ul> <p> Let's give a simple example:</p><pre class='brush:php;toolbar:false;'> // math.cppm export module math; export int add(int a, int b) { return ab; } // main.cpp import math; int main() { return add(1, 2); }</pre><p> At present, the support for modules by mainstream compilers is still gradually improving, but it has begun to be used in experimental projects. </p><img src="/static/imghw/default1.png" data-src="https://img.php.cn/upload/article/000/000/000/175234567522217.jpeg" class="lazy" alt="C tutorial covering C 20 new features" /><hr /><h3 id="Ranges"> Ranges</h3><p> The scope library is a very practical new component in the C 20 standard library. It simplifies the operation of containers, such as filtering, conversion, etc.</p><ul><li> Use <code>std::views::filter</code> and <code>std::views::transform</code> to write chain operations similar to Python.</li><li> No more need to write a lot of loops and intermediate variables.</li></ul><p> For example:</p><pre class='brush:php;toolbar:false;'> #include <vector> #include <ranges> #include <iostream> int main() { std::vector<int> v = {1, 2, 3, 4, 5, 6}; auto even = v | std::views::filter([](int i){ return i % 2 == 0; }); for (int i : even) { std::cout << i << " "; } }</pre><p> Output: <code>2 4 6</code></p><p> This feature is especially suitable for handling data streams or for functional-style programming.</p><hr /><h3 id="Coroutines"> Coroutines</h3><p> Coroutines allow you to maintain a synchronous style when writing asynchronous code and have clearer logic, especially suitable for scenarios such as network requests and task scheduling.</p><ul><li> Use <code>co_await</code> , <code>co_yield</code> , <code>co_return</code> to control the process.</li><li> It needs to be used with the return type (such as <code>std::future</code> , <code>std::generator</code> ).</li></ul><p> Simple example:</p><pre class='brush:php;toolbar:false;'> #include <coroutine> #include <iostream> struct [[nodiscard]] Task { struct promise_type { Task get_return_object() { return {}; } std::suspend_never initial_suspend() { return {}; } std::suspend_never final_suspend() noexcept { return {}; } void return_void() {} void unhandled_exception() {} }; }; Task countNumbers() { for (int i = 1; i <= 3; i) { std::cout << i << " "; co_await std::suspend_always{}; } }</pre><p> The coroutine mechanism is relatively complex, so it is recommended to start with the generator or future provided by the standard library.</p><hr /><h3 id="Three-way-comparison-operator"> Three-way comparison operator (<=>)</h3><p> C 20 introduces the "spaceship operator" <code><=></code> , which can automatically deduce various comparative relationships between objects.</p><ul><li> Just define <code><=></code> once and the compiler can automatically generate <code>==</code> , <code>!=</code> , <code><</code> , <code><=</code> , <code>></code> , <code>>=</code> .</li><li> Reduce boilerplate code drastically.</li></ul><p> For example:</p><pre class='brush:php;toolbar:false;'> struct Point { int x, y; auto operator<=>(const Point&) const = default; };</pre><p> In this way, the Point type can be compared directly with all comparison operators.</p> <hr> <p> Basically that's it. Although there are many new features in C 20, many of them can already be tried in actual projects, especially features such as range, module and three-way comparisons that can significantly improve the quality of the code. You may be a little uncomfortable at first, but once you master it, you will find that writing code has become easier.</p>

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