{"id":1014,"date":"2020-05-08T17:00:07","date_gmt":"2020-05-08T09:00:07","guid":{"rendered":"https:\/\/beijian99.top\/?p=1014"},"modified":"2025-05-10T09:06:28","modified_gmt":"2025-05-10T01:06:28","slug":"c-11-%e6%96%b0%e7%89%b9%e6%80%a7","status":"publish","type":"post","link":"https:\/\/beijian99.top\/?p=1014","title":{"rendered":"C++ 11 \u65b0\u7279\u6027"},"content":{"rendered":"\n

\u4e00\u3001\u81ea\u52a8\u7c7b\u578b\u63a8\u5bfc<\/p>\n\n\n\n

    \n
  1. auto<\/code> \u5173\u952e\u5b57<\/li>\n<\/ol>\n\n\n\n
    auto i = 42;          \/\/ i \u662f int \u7c7b\u578b
    auto d = 3.14;        \/\/ d \u662f double \u7c7b\u578b
    auto s = \"hello\";     \/\/ s \u662f const char* \u7c7b\u578b

    std::vector<int> vec;
    auto it = vec.begin(); \/\/ it \u662f std::vector<int>::iterator \u7c7b\u578b<\/code><\/pre>\n\n\n\n
      \n
    1. decltype<\/code> \u5173\u952e\u5b57<\/li>\n<\/ol>\n\n\n\n
      int x = 10;
      decltype(x) y = 20;   \/\/ y \u7684\u7c7b\u578b\u4e0e x \u76f8\u540c (int)

      const std::vector<int> vec;
      decltype(vec.size()) size = vec.size(); \/\/ size_t \u7c7b\u578b<\/code><\/pre>\n\n\n\n
      \u4e8c\u3001\u667a\u80fd\u6307\u9488<\/p>\n\n\n\n
        \n
      1. unique_ptr<\/code> (\u72ec\u5360\u6240\u6709\u6743)<\/li>\n<\/ol>\n\n\n\n
        #include <memory>
        std::unique_ptr<int> p1(new int(10));
        \/\/ std::unique_ptr<int> p2 = p1; \/\/ \u9519\u8bef\uff0c\u4e0d\u80fd\u590d\u5236
        std::unique_ptr<int> p2 = std::move(p1); \/\/ \u53ef\u4ee5\u79fb\u52a8<\/code><\/pre>\n\n\n\n
          \n
        1. shared_ptr<\/code> (\u5171\u4eab\u6240\u6709\u6743)<\/li>\n<\/ol>\n\n\n\n
          std::shared_ptr<int> p1(new int(20));
          std::shared_ptr<int> p2 = p1; \/\/ \u5f15\u7528\u8ba1\u6570\u589e\u52a0<\/code><\/pre>\n\n\n\n
            \n
          1. weak_ptr<\/code> (\u5f31\u5f15\u7528)<\/li>\n<\/ol>\n\n\n\n
            std::shared_ptr<int> sp(new int(30));
            std::weak_ptr<int> wp = sp;

            if (auto locked = wp.lock()) { \/\/ \u5c1d\u8bd5\u83b7\u53d6 shared_ptr
                \/\/ \u4f7f\u7528 locked
            }<\/code><\/pre>\n\n\n\n
            \u4e09\u3001\u53f3\u503c\u5f15\u7528\u548c\u79fb\u52a8\u8bed\u4e49<\/p>\n\n\n\n
              \n
            1. \u53f3\u503c\u5f15\u7528 (&&<\/code>)<\/li>\n<\/ol>\n\n\n\n
              void process(int& x) { \/* \u5904\u7406\u5de6\u503c *\/ }
              void process(int&& x) { \/* \u5904\u7406\u53f3\u503c *\/ }

              int a = 10;
              process(a);   \/\/ \u8c03\u7528\u5de6\u503c\u7248\u672c
              process(20);  \/\/ \u8c03\u7528\u53f3\u503c\u7248\u672c<\/code><\/pre>\n\n\n\n
                \n
              1. \u79fb\u52a8\u6784\u9020\u51fd\u6570\u548c\u79fb\u52a8\u8d4b\u503c\u8fd0\u7b97\u7b26<\/li>\n<\/ol>\n\n\n\n
                class MyString {
                    char* data;
                public:
                    \/\/ \u79fb\u52a8\u6784\u9020\u51fd\u6570
                    MyString(MyString&& other) noexcept 
                        : data(other.data) {
                        other.data = nullptr;
                    }
                    
                    \/\/ \u79fb\u52a8\u8d4b\u503c\u8fd0\u7b97\u7b26
                    MyString& operator=(MyString&& other) noexcept {
                        if (this != &other) {
                            delete[] data;
                            data = other.data;
                            other.data = nullptr;
                        }
                        return *this;
                    }
                };<\/code><\/pre>\n\n\n\n
                  \n
                1. std::move<\/code><\/li>\n<\/ol>\n\n\n\n
                  std::vector<std::string> v1, v2;
                  v1.push_back(\"hello\");
                  v2.push_back(std::move(v1[0])); \/\/ \u79fb\u52a8\u800c\u975e\u590d\u5236<\/code><\/pre>\n\n\n\n
                  \u56db\u3001Lambda \u8868\u8fbe\u5f0f<\/p>\n\n\n\n
                  auto add = [](int a, int b) { return a + b; };
                  int sum = add(3, 4);

                  \/\/ \u6355\u83b7\u5217\u8868
                  int x = 10;
                  auto print_x = [x]() { std::cout << x; };
                  print_x();

                  \/\/ mutable Lambda
                  auto counter = [count = 0]() mutable { return ++count; };<\/code><\/pre>\n\n\n\n
                  \u4e94\u3001\u57fa\u4e8e\u8303\u56f4\u7684 for \u5faa\u73af<\/p>\n\n\n\n
                  std::vector<int> vec = {1, 2, 3, 4};

                  \/\/ \u503c\u62f7\u8d1d\u65b9\u5f0f
                  for (int x : vec) {
                      std::cout << x << \" \";
                  }

                  \/\/ \u5f15\u7528\u65b9\u5f0f\u4fee\u6539
                  for (int& x : vec) {
                      x *= 2;
                  }

                  \/\/ const \u5f15\u7528
                  for (const int& x : vec) {
                      std::cout << x << \" \";
                  }<\/code><\/pre>\n\n\n\n
                  \u516d\u3001\u521d\u59cb\u5316\u5217\u8868<\/p>\n\n\n\n
                    \n
                  1. \u7edf\u4e00\u521d\u59cb\u5316\u8bed\u6cd5<\/li>\n<\/ol>\n\n\n\n
                    int x{10};              \/\/ \u66ff\u4ee3 int x = 10;
                    std::vector<int> v{1, 2, 3}; \/\/ \u521d\u59cb\u5316\u5217\u8868<\/code><\/pre>\n\n\n\n
                      \n
                    1. \u7c7b\u6210\u5458\u521d\u59cb\u5316<\/li>\n<\/ol>\n\n\n\n
                      class MyClass {
                          int x = 10; \/\/ C++11 \u7c7b\u6210\u5458\u521d\u59cb\u5316
                          std::string s{\"hello\"};
                      };<\/code><\/pre>\n\n\n\n
                      \u4e03\u3001nullptr<\/code><\/p>\n\n\n\n
                      void foo(int* p) {}

                      foo(NULL);    \/\/ \u53ef\u80fd\u6709\u95ee\u9898\uff0cNULL \u53ef\u80fd\u662f 0
                      foo(nullptr); \/\/ \u660e\u786e\u8868\u793a\u7a7a\u6307\u9488<\/code><\/pre>\n\n\n\n
                      \u516b\u3001\u5f3a\u7c7b\u578b\u679a\u4e3e<\/p>\n\n\n\n
                      enum class Color { Red, Green, Blue }; \/\/ \u4f5c\u7528\u57df\u679a\u4e3e

                      Color c = Color::Red;
                      \/\/ int i = Color::Red; \/\/ \u9519\u8bef\uff0c\u4e0d\u80fd\u9690\u5f0f\u8f6c\u6362<\/code><\/pre>\n\n\n\n
                      \u4e5d\u3001constexpr<\/code><\/p>\n\n\n\n
                      constexpr int square(int x) {
                          return x * x;
                      }

                      int array[square(5)]; \/\/ \u7f16\u8bd1\u65f6\u8ba1\u7b97<\/code><\/pre>\n\n\n\n
                      \u5341\u3001\u59d4\u6258\u6784\u9020\u51fd\u6570<\/p>\n\n\n\n
                      cpp\u590d\u5236class MyClass {\n    int x, y;\npublic:\n    MyClass(int a) : x(a), y(0) {}\n    MyClass() : MyClass(0) {} \/\/ \u59d4\u6258\u7ed9\u53e6\u4e00\u4e2a\u6784\u9020\u51fd\u6570\n};<\/code><\/pre>\n\n\n\n
                      \u5341\u4e00\u3001override<\/code> \u548c final<\/code><\/p>\n\n\n\n
                      class Base {
                      public:
                          virtual void foo() const;
                          virtual void bar() final; \/\/ \u7981\u6b62\u6d3e\u751f\u7c7b\u91cd\u5199
                      };

                      class Derived : public Base {
                      public:
                          void foo() const override; \/\/ \u660e\u786e\u8868\u793a\u91cd\u5199
                          \/\/ void bar() override; \/\/ \u9519\u8bef\uff0c\u57fa\u7c7b\u5df2\u58f0\u660e final
                      };<\/code><\/pre>\n\n\n\n
                      \u5341\u4e8c\u3001\u53d8\u957f\u6a21\u677f<\/p>\n\n\n\n
                      template<typename... Args>
                      void print(Args... args) {
                          (std::cout << ... << args) << '\\n'; \/\/ C++17 \u6298\u53e0\u8868\u8fbe\u5f0f
                      }

                      print(1, 2.5, \"hello\"); \/\/ \u63a5\u53d7\u4efb\u610f\u6570\u91cf\u53c2\u6570<\/code><\/pre>\n\n\n\n
                      \u5341\u4e09\u3001\u7ebf\u7a0b\u652f\u6301<\/p>\n\n\n\n
                      #include <thread>
                      #include <mutex>

                      std::mutex mtx;

                      void task() {
                          std::lock_guard<std::mutex> lock(mtx);
                          \/\/ \u4e34\u754c\u533a\u4ee3\u7801
                      }

                      int main() {
                          std::thread t1(task);
                          std::thread t2(task);
                          t1.join();
                          t2.join();
                      }<\/code><\/pre>\n\n\n\n
                      \u5341\u56db\u3001std::function<\/code> \u548c std::bind<\/code><\/p>\n\n\n\n
                      #include <functional>

                      int add(int a, int b) { return a + b; }

                      int main() {
                          std::function<int(int, int)> func = add;
                          auto bound = std::bind(func, 10, std::placeholders::_1);
                          int result = bound(20); \/\/ \u76f8\u5f53\u4e8e add(10, 20)
                      }<\/code><\/pre>\n\n\n\n
                      \u5341\u4e94\u3001std::array<\/code><\/p>\n\n\n\n
                      #include <array>

                      std::array<int, 5> arr = {1, 2, 3, 4, 5};
                      for (auto x : arr) {
                          std::cout << x << \" \";
                      }<\/code><\/pre>\n\n\n\n
                      \u5341\u516d\u3001std::tuple<\/code><\/p>\n\n\n\n
                      #include <tuple>

                      auto t = std::make_tuple(1, 2.5, \"hello\");
                      int x = std::get<0>(t); \/\/ \u83b7\u53d6\u7b2c\u4e00\u4e2a\u5143\u7d20<\/code><\/pre>\n\n\n\n
                      \u5341\u4e03\u3001\u7c7b\u578b\u522b\u540d (using<\/code>)<\/p>\n\n\n\n
                      using IntVector = std::vector<int>; \/\/ \u66ff\u4ee3 typedef

                      template<typename T>
                      using MyMap = std::map<int, T>;<\/code><\/pre>\n\n\n\n
                      \u5341\u516b\u3001\u9759\u6001\u65ad\u8a00 (static_assert<\/code>)<\/p>\n\n\n\n
                      static_assert(sizeof(int) == 4, \"int must be 4 bytes\");<\/code><\/pre>\n\n\n\n
                      \u5341\u4e5d\u3001noexcept<\/code><\/p>\n\n\n\n
                      void foo() noexcept { \/\/ \u4fdd\u8bc1\u4e0d\u629b\u51fa\u5f02\u5e38
                          \/\/ ...
                      }<\/code><\/pre>\n\n\n\n
                      \u4e8c\u5341\u3001\u539f\u59cb\u5b57\u7b26\u4e32\u5b57\u9762\u91cf<\/p>\n\n\n\n
                      const char* path = R\"(C:\\Program Files\\MyApp)\";
                      const char* html = R\"(
                      <html>
                          <body>Hello<\/body>
                      <\/html>
                      )\";<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
                      \u4e00\u3001\u81ea\u52a8\u7c7b\u578b\u63a8\u5bfc auto i = 42; \/\/ i \u662f int \u7c7b\u578bauto d = 3.14; \/\/ d  […]<\/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-1014","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\/1014","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=1014"}],"version-history":[{"count":2,"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/posts\/1014\/revisions"}],"predecessor-version":[{"id":1052,"href":"https:\/\/beijian99.top\/index.php?rest_route=\/wp\/v2\/posts\/1014\/revisions\/1052"}],"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=1014"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1014"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/beijian99.top\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1014"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}