{"id":1016,"date":"2020-05-08T17:03:54","date_gmt":"2020-05-08T09:03:54","guid":{"rendered":"https:\/\/beijian99.top\/?p=1016"},"modified":"2025-05-08T17:28:24","modified_gmt":"2025-05-08T09:28:24","slug":"c14-%e6%96%b0%e7%89%b9%e6%80%a7","status":"publish","type":"post","link":"https:\/\/beijian99.top\/?p=1016","title":{"rendered":"C++14 \u65b0\u7279\u6027"},"content":{"rendered":"\n

\u4e00\u3001\u51fd\u6570\u8fd4\u56de\u7c7b\u578b\u63a8\u5bfc\u589e\u5f3a<\/p>\n\n\n\n

    \n
  1. \u666e\u901a\u51fd\u6570\u8fd4\u56de\u7c7b\u578b\u63a8\u5bfc<\/li>\n<\/ol>\n\n\n\n
    \/\/ C++11 \u9700\u8981\u5c3e\u7f6e\u8fd4\u56de\u7c7b\u578b
    auto add(int a, int b) -> int { return a + b; }

    \/\/ C++14 \u53ef\u4ee5\u76f4\u63a5\u63a8\u5bfc
    auto add(int a, int b) { return a + b; }<\/code><\/pre>\n\n\n\n
      \n
    1. decltype(auto)<\/code> \u8fd4\u56de\u7c7b\u578b<\/li>\n<\/ol>\n\n\n\n
      int& get_ref(int& x) { return x; }

      \/\/ C++11 \u65b9\u5f0f
      auto get_ref11(int& x) -> int& { return x; }

      \/\/ C++14 \u66f4\u7b80\u6d01
      decltype(auto) get_ref14(int& x) { return x; }<\/code><\/pre>\n\n\n\n
      \u4e8c\u3001\u6cdb\u578b Lambda \u8868\u8fbe\u5f0f<\/p>\n\n\n\n
        \n
      1. \u53c2\u6570\u7c7b\u578b\u4f7f\u7528 auto<\/code><\/li>\n<\/ol>\n\n\n\n
        \/\/ C++11 Lambda \u5fc5\u987b\u6307\u5b9a\u53c2\u6570\u7c7b\u578b
        auto lambda11 = [](int x, int y) { return x + y; };

        \/\/ C++14 \u6cdb\u578b Lambda
        auto lambda14 = [](auto x, auto y) { return x + y; };

        \/\/ \u4f7f\u7528
        int i = lambda14(3, 4);       \/\/ int \u7248\u672c
        double d = lambda14(3.5, 4.5); \/\/ double \u7248\u672c<\/code><\/pre>\n\n\n\n
          \n
        1. Lambda \u6355\u83b7\u8868\u8fbe\u5f0f<\/li>\n<\/ol>\n\n\n\n
          int x = 10;

          \/\/ C++11 \u53ea\u80fd\u6355\u83b7\u53d8\u91cf
          auto lambda11 = [x]() { return x; };

          \/\/ C++14 \u53ef\u4ee5\u6355\u83b7\u8868\u8fbe\u5f0f\u7ed3\u679c
          auto lambda14 = [value = x * 2]() { return value; };<\/code><\/pre>\n\n\n\n
          \u4e09\u3001\u53d8\u91cf\u6a21\u677f<\/p>\n\n\n\n
          \/\/ C++11 \u53ea\u6709\u7c7b\u6a21\u677f\u548c\u51fd\u6570\u6a21\u677f
          template<typename T>
          constexpr T pi = T(3.1415926535897932385);

          \/\/ \u4f7f\u7528
          float f = pi<float>;
          double d = pi<double>;<\/code><\/pre>\n\n\n\n
          \u56db\u3001\u4e8c\u8fdb\u5236\u5b57\u9762\u91cf<\/p>\n\n\n\n
          int x = 0b101010; \/\/ \u4e8c\u8fdb\u5236\u8868\u793a\uff0c\u7b49\u4e8e\u5341\u8fdb\u5236\u768442<\/code><\/pre>\n\n\n\n
          \u4e94\u3001\u6570\u5b57\u5206\u9694\u7b26<\/p>\n\n\n\n
          int million = 1'000'000;
          double pi = 3.141'592'653'589'793;<\/code><\/pre>\n\n\n\n
          \u516d\u3001[[deprecated]]<\/code> \u5c5e\u6027<\/p>\n\n\n\n
          [[deprecated(\"Use new_func() instead\")]]
          void old_func() {}

          \/\/ \u4f7f\u7528\u65f6\u7f16\u8bd1\u5668\u4f1a\u53d1\u51fa\u8b66\u544a
          old_func();<\/code><\/pre>\n\n\n\n
          \u4e03\u3001constexpr<\/code> \u51fd\u6570\u589e\u5f3a<\/p>\n\n\n\n
            \n
          1. \u5141\u8bb8\u5c40\u90e8\u53d8\u91cf\u548c\u5faa\u73af<\/li>\n<\/ol>\n\n\n\n
            constexpr int factorial(int n) {
                int result = 1;
                for (int i = 1; i <= n; ++i) {
                    result *= i;
                }
                return result;
            }

            constexpr int fact5 = factorial(5); \/\/ 120<\/code><\/pre>\n\n\n\n
              \n
            1. \u5141\u8bb8 if<\/code> \u8bed\u53e5<\/li>\n<\/ol>\n\n\n\n
              constexpr bool is_even(int x) {
                  if (x % 2 == 0) {
                      return true;
                  } else {
                      return false;
                  }
              }<\/code><\/pre>\n\n\n\n
              \u516b\u3001std::make_unique<\/code><\/p>\n\n\n\n
              #include <memory>

              \/\/ C++11 \u53ea\u6709 std::make_shared
              auto sp = std::make_shared<int>(42);

              \/\/ C++14 \u65b0\u589e std::make_unique
              auto up = std::make_unique<int>(42);<\/code><\/pre>\n\n\n\n
              \u4e5d\u3001std::integer_sequence<\/code><\/p>\n\n\n\n
              #include <utility>

              template<typename T, T... Ints>
              void print_sequence(std::integer_sequence<T, Ints...>) {
                  ((std::cout << Ints << ' '), ...); \/\/ C++17 \u6298\u53e0\u8868\u8fbe\u5f0f
              }

              \/\/ \u4f7f\u7528
              print_sequence(std::integer_sequence<int, 1, 2, 3>{}); \/\/ \u8f93\u51fa: 1 2 3<\/code><\/pre>\n\n\n\n
              \u5341\u3001std::exchange<\/code><\/p>\n\n\n\n
              #include <utility>

              int x = 10;
              int old = std::exchange(x, 20); \/\/ old=10, x=20<\/code><\/pre>\n\n\n\n
              \u5341\u4e00\u3001std::quoted<\/code><\/p>\n\n\n\n
              #include <iomanip>
              #include <string>

              std::string s = \"Hello\";
              std::cout << std::quoted(s); \/\/ \u8f93\u51fa: \"Hello\"<\/code><\/pre>\n\n\n\n
              \u5341\u4e8c\u3001std::shared_timed_mutex<\/code><\/p>\n\n\n\n
              #include <shared_mutex>

              std::shared_timed_mutex mtx;

              \/\/ \u8bfb\u9501\uff08\u5171\u4eab\u9501\uff09
              {
                  std::shared_lock<std::shared_timed_mutex> lock(mtx);
                  \/\/ \u8bfb\u53d6\u64cd\u4f5c
              }

              \/\/ \u5199\u9501\uff08\u72ec\u5360\u9501\uff09
              {
                  std::unique_lock<std::shared_timed_mutex> lock(mtx);
                  \/\/ \u5199\u5165\u64cd\u4f5c
              }<\/code><\/pre>\n\n\n\n
              \u5341\u4e09\u3001std::cbegin<\/code>\/std::cend<\/code> \u7b49<\/p>\n\n\n\n
              #include <vector>\n#include <iterator>\n\nstd::vector<int> v = {1, 2, 3};\n\n\/\/ C++11 \u65b9\u5f0f\nauto it11 = v.cbegin();\n\n\/\/ C++14 \u66f4\u901a\u7528\u7684\u65b9\u5f0f\nauto it14 = std::cbegin(v);<\/code><\/code><\/pre>\n\n\n\n
              \u5341\u56db\u3001\u805a\u5408\u6210\u5458\u521d\u59cb\u5316<\/p>\n\n\n\n
              struct Point {\n    int x, y;\n};\n\n\/\/ C++11 \u9700\u8981\u6784\u9020\u51fd\u6570\u6216\u521d\u59cb\u5316\u5217\u8868\nPoint p1{1, 2};\n\n\/\/ C++14 \u53ef\u4ee5\u76f4\u63a5\u521d\u59cb\u5316\nPoint p2{1}; \/\/ p2.x=1, p2.y=0<\/code><\/code><\/pre>\n\n\n\n
              \u5341\u4e94\u3001std::tuple<\/code> \u5143\u7d20\u8bbf\u95ee<\/p>\n\n\n\n
              #include <tuple>\n\nauto t = std::make_tuple(1, 2.5, \"hello\");\n\n\/\/ C++11 \u53ea\u80fd\u901a\u8fc7 std::get<index>\nint x = std::get<0>(t);\n\n\/\/ C++14 \u53ef\u4ee5\u901a\u8fc7\u7c7b\u578b\u83b7\u53d6\ndouble d = std::get<double>(t); \/\/ \u83b7\u53d6 double \u7c7b\u578b\u7684\u5143\u7d20<\/code><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
              \u4e00\u3001\u51fd\u6570\u8fd4\u56de\u7c7b\u578b\u63a8\u5bfc\u589e\u5f3a \/\/ C++11 \u9700\u8981\u5c3e\u7f6e\u8fd4\u56de\u7c7b\u578bauto add(int a, int b) -> […]<\/p>\n","protected":false},"author":1,"featured_media":1021,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[153],"tags":[154],"class_list":["post-1016","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-cpp","tag-cpp"],"_links":{"self":[{"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/posts\/1016","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1016"}],"version-history":[{"count":2,"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/posts\/1016\/revisions"}],"predecessor-version":[{"id":1018,"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/posts\/1016\/revisions\/1018"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/media\/1021"}],"wp:attachment":[{"href":"https:\/\/beijian99.top\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1016"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1016"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1016"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}