{"id":7421,"date":"2026-07-22T11:54:22","date_gmt":"2026-07-22T03:54:22","guid":{"rendered":"https:\/\/i007.cc\/wordpress\/?p=7421"},"modified":"2026-07-22T11:54:22","modified_gmt":"2026-07-22T03:54:22","slug":"c%e9%ab%98%e7%ba%a7%e7%89%b9%e6%80%a7%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/7421","title":{"rendered":"C++\u9ad8\u7ea7\u7279\u6027\u8be6\u89e3"},"content":{"rendered":"

\ud83d\udd37 \u4e00\u3001mutable<\/code>\uff1a\u8ba9\u503c\u6355\u83b7\u53ef\u4fee\u6539<\/h3>\n

\u503c\u6355\u83b7\u9ed8\u8ba4\u662f const<\/code>\uff0c\u52a0 mutable<\/code> \u540e\u53ef\u4ee5\u4fee\u6539\u526f\u672c<\/strong>\uff08\u4e0d\u5f71\u54cd\u5916\u90e8\uff09\uff1a<\/p>\n

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cpp<\/div>\n
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int count = 0;\r\n\r\nauto counter = [count]() mutable {\r\n    count++;           \/\/ \u2705 \u4fee\u6539\u7684\u662f\u526f\u672c\r\n    return count;\r\n};\r\n\r\ncounter();  \/\/ \u2192 1\r\ncounter();  \/\/ \u2192 2\r\ncount;      \/\/ \u2192 0\uff0c\u5916\u90e8\u5b8c\u5168\u4e0d\u53d7\u5f71\u54cd\uff01<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
\u5bf9\u6bd4\u5f15\u7528\u6355\u83b7\uff1a<\/p>\n
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cpp<\/div>\n
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auto counter2 = [&count]() {\r\n    count++;\r\n};\r\n\r\ncounter2();  \/\/ count \u2192 1\r\ncounter2();  \/\/ count \u2192 2\r\ncount;       \/\/ \u2192 2\uff0c\u5916\u90e8\u88ab\u4fee\u6539\u4e86<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
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\u9009\u62e9\u539f\u5219<\/strong>\uff1a\u60f3\u8981”\u5185\u90e8\u8ba1\u6570”\u4f46\u4e0d\u6c61\u67d3\u5916\u90e8 \u2192 mutable<\/code> \u503c\u6355\u83b7\uff1b\u60f3\u540c\u6b65\u5916\u90e8\u72b6\u6001 \u2192 \u5f15\u7528\u6355\u83b7\u3002<\/p>\n<\/blockquote>\n
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\ud83d\udd37 \u4e8c\u3001STL \u7b97\u6cd5\u4e2d\u7684 Lambda \u5b9e\u6218<\/h3>\n
sort<\/code> \u2014 \u81ea\u5b9a\u4e49\u6392\u5e8f<\/h4>\n
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cpp<\/div>\n
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std::vector<std::string> words = {\"banana\", \"apple\", \"cherry\", \"fig\"};\r\n\r\n\/\/ \u6309\u5b57\u7b26\u4e32\u957f\u5ea6\u6392\u5e8f\r\nstd::sort(words.begin(), words.end(),\r\n    [](const std::string& a, const std::string& b) {\r\n        return a.size() < b.size();\r\n    });\r\n\/\/ \u2192 fig, apple, banana, cherry<\/pre>\n
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find_if<\/code> \u2014 \u6761\u4ef6\u67e5\u627e<\/h4>\n
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cpp<\/div>\n
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std::vector<int> v = {3, 7, 2, 9, 4};\r\n\r\nint threshold = 6;\r\nauto it = std::find_if(v.begin(), v.end(),\r\n    [threshold](int x) { return x > threshold; }  \/\/ \u6355\u83b7\u9608\u503c\r\n);\r\n\r\nif (it != v.end())\r\n    std::cout << *it;  \/\/ \u2192 7\uff08\u7b2c\u4e00\u4e2a\u5927\u4e8e6\u7684\u5143\u7d20\uff09<\/pre>\n
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transform<\/code> \u2014 \u6279\u91cf\u53d8\u6362<\/h4>\n
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cpp<\/div>\n
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std::vector<int> v = {1, 2, 3, 4, 5};\r\nstd::vector<int> result(v.size());\r\n\r\nstd::transform(v.begin(), v.end(), result.begin(),\r\n    [](int x) { return x * x; }\r\n);\r\n\/\/ result \u2192 {1, 4, 9, 16, 25}<\/pre>\n
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for_each<\/code> + remove_if<\/code> \u2014 \u8fc7\u6ee4<\/h4>\n
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cpp<\/div>\n
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std::vector<int> v = {1, 2, 3, 4, 5, 6};\r\n\r\n\/\/ \u5220\u9664\u6240\u6709\u5076\u6570\r\nv.erase(\r\n    std::remove_if(v.begin(), v.end(),\r\n        [](int x) { return x % 2 == 0; }),\r\n    v.end()\r\n);\r\n\/\/ v \u2192 {1, 3, 5}<\/pre>\n
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\ud83d\udd37 \u4e09\u3001\u5e76\u53d1\u4e2d\u7684 Lambda \u914d\u5408 std::thread<\/code><\/h3>\n
\u57fa\u672c\u7528\u6cd5<\/h4>\n
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cpp<\/div>\n
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#include <thread>\r\n\r\nstd::thread t([]() {\r\n    std::cout << \"\u5b50\u7ebf\u7a0b\u8fd0\u884c\u4e2d\" << std::endl;\r\n});\r\n\r\nt.join();  \/\/ \u4e3b\u7ebf\u7a0b\u7b49\u5f85\u5b50\u7ebf\u7a0b\u7ed3\u675f<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
\u4f20\u53c2\u7ed9\u7ebf\u7a0b<\/h4>\n
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cpp<\/div>\n
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auto task = [](int id, std::string msg) {\r\n    std::cout << \"\u7ebf\u7a0b\" << id << \": \" << msg << std::endl;\r\n};\r\n\r\nstd::thread t1(task, 1, \"hello\");\r\nstd::thread t2(task, 2, \"world\");\r\n\r\nt1.join();\r\nt2.join();<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
\u26a0\ufe0f \u5e76\u53d1\u4e2d\u7684\u5f15\u7528\u6355\u83b7\u9677\u9631<\/h4>\n
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cpp<\/div>\n
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\/\/ \u274c \u5371\u9669\uff1a\u4e3b\u7ebf\u7a0b\u7ed3\u675f\u540e data \u5df2\u9500\u6bc1\r\nstd::vector<int> data = {1, 2, 3};\r\nstd::thread t([&data]() {\r\n    \/\/ \u5982\u679c\u4e3b\u7ebf\u7a0b\u5148\u7ed3\u675f\uff0cdata \u60ac\u7a7a\uff01\r\n    for (auto x : data) std::cout << x;\r\n});\r\nt.detach();  \/\/ detach \u540e\u4e3b\u7ebf\u7a0b\u4e0d\u7b49\u5b50\u7ebf\u7a0b\uff0c\u6781\u5ea6\u5371\u9669\r\n\r\n\r\n\/\/ \u2705 \u5b89\u5168\uff1a\u503c\u6355\u83b7\uff0c\u62f7\u8d1d\u4e00\u4efd\u7ed9\u7ebf\u7a0b\r\nstd::thread t([data]() {  \/\/ \u62f7\u8d1d data\r\n    for (auto x : data) std::cout << x;\r\n});\r\nt.join();  \/\/ \u6216\u786e\u4fdd join \u5728 data \u9500\u6bc1\u524d<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
\u5171\u4eab\u6570\u636e\u7528 mutex<\/code> \u4fdd\u62a4<\/h4>\n
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cpp<\/div>\n
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#include <mutex>\r\n\r\nint total = 0;\r\nstd::mutex mtx;\r\n\r\nauto addTask = [&total, &mtx](int val) {\r\n    std::lock_guard<std::mutex> lock(mtx);  \/\/ \u81ea\u52a8\u52a0\u9501\/\u89e3\u9501\r\n    total += val;\r\n};\r\n\r\nstd::thread t1(addTask, 10);\r\nstd::thread t2(addTask, 20);\r\nt1.join();\r\nt2.join();\r\n\r\nstd::cout << total;  \/\/ \u2192 30\uff0c\u5b89\u5168\uff01<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
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\ud83d\udd37 \u7efc\u5408\u5bf9\u6bd4\u603b\u7ed3<\/h3>\n
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Lambda \u80fd\u529b\u56fe\uff1a\r\n\r\n\u5b9a\u4e49\u65f6\u7ed1\u5b9a\u73af\u5883          \u8c03\u7528\u65f6\u63a5\u6536\u6570\u636e\r\n   [\u6355\u83b7]        +         (\u4f20\u53c2)          =   \u5b8c\u6574\u7684\"\u5c0f\u51fd\u6570\"\r\n     \u2193                        \u2193\r\n  \u503c\u6355\u83b7(\u5feb\u7167)           \u666e\u901a\u53c2\u6570\r\n  \u5f15\u7528\u6355\u83b7(\u5171\u4eab)\r\n  mutable(\u53ef\u6539\u526f\u672c)\r\n     \u2193\r\n  \u7528\u4e8e STL \u7b97\u6cd5 \/ \u7ebf\u7a0b \/ \u56de\u8c03 \/ \u5f02\u6b65\u4efb\u52a1<\/pre>\n
 <\/p>\n<\/div>\n<\/div>\n
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\u4e0b\u4e00\u6b65\u53ef\u4ee5\u7ee7\u7eed\u5b66\uff1a<\/p>\n
    \n
  • std::async<\/code> \/ std::future<\/code><\/strong>\uff1a\u66f4\u9ad8\u7ea7\u7684\u5f02\u6b65\u4efb\u52a1<\/li>\n
  • \u6a21\u677f + Lambda<\/strong>\uff1a\u6cdb\u578b\u56de\u8c03<\/li>\n
  • C++20 \u7684 Lambda \u65b0\u7279\u6027<\/strong>\uff08\u6a21\u677fLambda\u3001[=, this]<\/code> \u7b49\uff09<\/li>\n<\/ul>\n
    \u60f3\u7ee7\u7eed\u54ea\u4e2a\uff1f<\/p>\n","protected":false},"excerpt":{"rendered":"
    \ud83d\udd37 \u4e00\u3001mutable\uff1a\u8ba9\u503c\u6355\u83b7\u53ef\u4fee\u6539 <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"colormag_page_container_layout":"default_layout","colormag_page_sidebar_layout":"default_layout","footnotes":""},"categories":[24],"tags":[],"class_list":["post-7421","post","type-post","status-publish","format-standard","hentry","category-value_docs"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7421","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/comments?post=7421"}],"version-history":[{"count":1,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7421\/revisions"}],"predecessor-version":[{"id":7422,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/7421\/revisions\/7422"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=7421"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=7421"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=7421"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}