{"id":1337,"date":"2018-06-04T23:53:39","date_gmt":"2018-06-04T15:53:39","guid":{"rendered":"https:\/\/damogame.cn:15443\/wordpress\/?p=1337"},"modified":"2018-06-04T23:53:39","modified_gmt":"2018-06-04T15:53:39","slug":"c11-%e6%99%ba%e8%83%bd%e6%8c%87%e9%92%88-unique_ptr%e3%80%81shared_ptr%e4%b8%8eweak_ptr","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/1337","title":{"rendered":"c++11 \u667a\u80fd\u6307\u9488 unique_ptr\u3001shared_ptr\u4e0eweak_ptr"},"content":{"rendered":"

c++11 \u667a\u80fd\u6307\u9488 unique_ptr\u3001shared_ptr\u4e0eweak_ptr<\/h1>\n

 <\/p>\n

C++11\u4e2d\u6709unique_ptr\u3001shared_ptr\u4e0eweak_ptr\u7b49\u667a\u80fd\u6307\u9488(smart pointer)\uff0c\u5b9a\u4e49\u5728<memory>\u4e2d\u3002<\/p>\n

\u53ef\u4ee5\u5bf9\u52a8\u6001\u8d44\u6e90\u8fdb\u884c\u7ba1\u7406\uff0c\u4fdd\u8bc1\u4efb\u4f55\u60c5\u51b5\u4e0b\uff0c\u5df2\u6784\u9020\u7684\u5bf9\u8c61\u6700\u7ec8\u4f1a\u9500\u6bc1\uff0c\u5373\u5b83\u7684\u6790\u6784\u51fd\u6570\u6700\u7ec8\u4f1a\u88ab\u8c03\u7528\u3002<\/p>\n

 <\/p>\n

unique_ptr<\/strong><\/p>\n

unique_ptr\u6301\u6709\u5bf9\u5bf9\u8c61\u7684\u72ec\u6709\u6743\uff0c\u540c\u4e00\u65f6\u523b\u53ea\u80fd\u6709\u4e00\u4e2aunique_ptr\u6307\u5411\u7ed9\u5b9a\u5bf9\u8c61\uff08\u901a\u8fc7\u7981\u6b62\u62f7\u8d1d\u8bed\u4e49\u3001\u53ea\u6709\u79fb\u52a8\u8bed\u4e49\u6765\u5b9e\u73b0\uff09\u3002<\/p>\n

unique_ptr\u6307\u9488\u672c\u8eab\u7684\u751f\u547d\u5468\u671f\uff1a\u4eceunique_ptr\u6307\u9488\u521b\u5efa\u65f6\u5f00\u59cb\uff0c\u76f4\u5230\u79bb\u5f00\u4f5c\u7528\u57df\u3002<\/p>\n

\u79bb\u5f00\u4f5c\u7528\u57df\u65f6\uff0c\u82e5\u5176\u6307\u5411\u5bf9\u8c61\uff0c\u5219\u5c06\u5176\u6240\u6307\u5bf9\u8c61\u9500\u6bc1(\u9ed8\u8ba4\u4f7f\u7528delete\u64cd\u4f5c\u7b26\uff0c\u7528\u6237\u53ef\u6307\u5b9a\u5176\u4ed6\u64cd\u4f5c)\u3002<\/p>\n

 <\/p>\n

\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n
#define _CRT_SECURE_NO_WARNINGS\r\n\r\n#include <iostream>\r\n#include <string>\r\n#include <memory>\r\n#include <vector>\r\n#include <map>\r\n\r\n\r\nvoid mytest()\r\n{\r\n    std::unique_ptr<int> up1(new int(11));   \/\/ \u65e0\u6cd5\u590d\u5236\u7684unique_ptr\r\n    \/\/unique_ptr<int> up2 = up1;        \/\/ err, \u4e0d\u80fd\u901a\u8fc7\u7f16\u8bd1\r\n    std::cout << *up1 << std::endl;   \/\/ 11\r\n\r\n    std::unique_ptr<int> up3 = std::move(up1);    \/\/ \u73b0\u5728p3\u662f\u6570\u636e\u7684\u552f\u4e00\u7684unique_ptr\r\n\r\n    std::cout << *up3 << std::endl;   \/\/ 11\r\n    \/\/std::cout << *up1 << std::endl;   \/\/ err, \u8fd0\u884c\u65f6\u9519\u8bef\r\n    up3.reset();            \/\/ \u663e\u5f0f\u91ca\u653e\u5185\u5b58\r\n    up1.reset();            \/\/ \u4e0d\u4f1a\u5bfc\u81f4\u8fd0\u884c\u65f6\u9519\u8bef\r\n    \/\/std::cout << *up3 << std::endl;   \/\/ err, \u8fd0\u884c\u65f6\u9519\u8bef\r\n\r\n    std::unique_ptr<int> up4(new int(22));   \/\/ \u65e0\u6cd5\u590d\u5236\u7684unique_ptr\r\n    up4.reset(new int(44)); \/\/\"\u7ed1\u5b9a\"\u52a8\u6001\u5bf9\u8c61\r\n    std::cout << *up4 << std::endl; \/\/ 44\r\n\r\n    up4 = nullptr;\/\/\u663e\u5f0f\u9500\u6bc1\u6240\u6307\u5bf9\u8c61\uff0c\u540c\u65f6\u667a\u80fd\u6307\u9488\u53d8\u4e3a\u7a7a\u6307\u9488\u3002\u4e0eup4.reset()\u7b49\u4ef7\r\n\r\n    std::unique_ptr<int> up5(new int(55));\r\n    int *p = up5.release(); \/\/\u53ea\u662f\u91ca\u653e\u63a7\u5236\u6743\uff0c\u4e0d\u4f1a\u91ca\u653e\u5185\u5b58\r\n    std::cout << *p << std::endl;\r\n    \/\/cout << *up5 << endl; \/\/ err, \u8fd0\u884c\u65f6\u9519\u8bef\r\n    delete p; \/\/\u91ca\u653e\u5806\u533a\u8d44\u6e90\r\n\r\n    return;\r\n}\r\n\r\nint main()\r\n{\r\n    mytest();\r\n\r\n    system(\"pause\");\r\n    return 0;\r\n}<\/pre>\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n<\/div>\n
 <\/p>\n
shared_ptr<\/p>\n
shared_ptr\u5141\u8bb8\u591a\u4e2a\u8be5\u667a\u80fd\u6307\u9488\u5171\u4eab\u7b2c\u201c\u62e5\u6709\u201d\u540c\u4e00\u5806\u5206\u914d\u5bf9\u8c61\u7684\u5185\u5b58\uff0c\u8fd9\u901a\u8fc7\u5f15\u7528\u8ba1\u6570\uff08reference counting\uff09\u5b9e\u73b0\uff0c\u4f1a\u8bb0\u5f55\u6709\u591a\u5c11\u4e2ashared_ptr\u5171\u540c\u6307\u5411\u4e00\u4e2a\u5bf9\u8c61\uff0c\u4e00\u65e6\u6700\u540e\u4e00\u4e2a\u8fd9\u6837\u7684\u6307\u9488\u88ab\u9500\u6bc1\uff0c\u4e5f\u5c31\u662f\u4e00\u65e6\u67d0\u4e2a\u5bf9\u8c61\u7684\u5f15\u7528\u8ba1\u6570\u53d8\u4e3a0\uff0c\u8fd9\u4e2a\u5bf9\u8c61\u4f1a\u88ab\u81ea\u52a8\u5220\u9664\u3002<\/p>\n
 <\/p>\n
\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n
#define _CRT_SECURE_NO_WARNINGS\r\n\r\n#include <iostream>\r\n#include <string>\r\n#include <memory>\r\n#include <vector>\r\n#include <map>\r\n\r\n\r\nvoid mytest()\r\n{\r\n    std::shared_ptr<int> sp1(new int(22));\r\n    std::shared_ptr<int> sp2 = sp1;\r\n    std::cout << \"cout: \" << sp2.use_count() << std::endl; \/\/ \u6253\u5370\u5f15\u7528\u8ba1\u6570\r\n\r\n    std::cout << *sp1 << std::endl;\r\n    std::cout << *sp2 << std::endl;\r\n\r\n    sp1.reset(); \/\/ \u663e\u793a\u8ba9\u5f15\u7528\u8ba1\u6570\u51cf\u4e00\r\n    std::cout << \"count: \" << sp2.use_count() << std::endl; \/\/ \u6253\u5370\u5f15\u7528\u8ba1\u6570\r\n\r\n    std::cout << *sp2 << std::endl; \/\/ 22\r\n\r\n    return;\r\n}\r\n\r\nint main()\r\n{\r\n    mytest();\r\n\r\n    system(\"pause\");\r\n    return 0;\r\n}<\/pre>\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n<\/div>\n
 <\/p>\n
weak_ptr<\/p>\n
weak_ptr\u662f\u4e3a\u914d\u5408shared_ptr\u800c\u5f15\u5165\u7684\u4e00\u79cd\u667a\u80fd\u6307\u9488\u6765\u534f\u52a9shared_ptr\u5de5\u4f5c\uff0c\u5b83\u53ef\u4ee5\u4ece\u4e00\u4e2ashared_ptr\u6216\u53e6\u4e00\u4e2aweak_ptr\u5bf9\u8c61\u6784\u9020\uff0c\u5b83\u7684\u6784\u9020\u548c\u6790\u6784\u4e0d\u4f1a\u5f15\u8d77\u5f15\u7528\u8ba1\u6570\u7684\u589e\u52a0\u6216\u51cf\u5c11\u3002\u6ca1\u6709\u91cd\u8f7d * \u548c -> \u4f46\u53ef\u4ee5\u4f7f\u7528lock\u83b7\u5f97\u4e00\u4e2a\u53ef\u7528\u7684shared_ptr\u5bf9\u8c61<\/p>\n
weak_ptr\u7684\u4f7f\u7528\u66f4\u4e3a\u590d\u6742\u4e00\u70b9\uff0c\u5b83\u53ef\u4ee5\u6307\u5411shared_ptr\u6307\u9488\u6307\u5411\u7684\u5bf9\u8c61\u5185\u5b58\uff0c\u5374\u5e76\u4e0d\u62e5\u6709\u8be5\u5185\u5b58\uff0c\u800c\u4f7f\u7528weak_ptr\u6210\u5458lock\uff0c\u5219\u53ef\u8fd4\u56de\u5176\u6307\u5411\u5185\u5b58\u7684\u4e00\u4e2ashare_ptr\u5bf9\u8c61\uff0c\u4e14\u5728\u6240\u6307\u5bf9\u8c61\u5185\u5b58\u5df2\u7ecf\u65e0\u6548\u65f6\uff0c\u8fd4\u56de\u6307\u9488\u7a7a\u503cnullptr\u3002<\/p>\n
\u6ce8\u610f\uff1aweak_ptr\u5e76\u4e0d\u62e5\u6709\u8d44\u6e90\u7684\u6240\u6709\u6743\uff0c\u6240\u4ee5\u4e0d\u80fd\u76f4\u63a5\u4f7f\u7528\u8d44\u6e90\u3002
\n\u53ef\u4ee5\u4ece\u4e00\u4e2aweak_ptr\u6784\u9020\u4e00\u4e2ashared_ptr\u4ee5\u53d6\u5f97\u5171\u4eab\u8d44\u6e90\u7684\u6240\u6709\u6743\u3002<\/p>\n
 <\/p>\n
\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n
#define _CRT_SECURE_NO_WARNINGS\r\n\r\n#include <iostream>\r\n#include <string>\r\n#include <memory>\r\n#include <vector>\r\n#include <map>\r\n\r\nvoid check(std::weak_ptr<int> &wp)\r\n{\r\n    std::shared_ptr<int> sp = wp.lock(); \/\/ \u8f6c\u6362\u4e3ashared_ptr<int>\r\n    if (sp != nullptr)\r\n    {\r\n        std::cout << \"still: \" << *sp << std::endl;\r\n    } \r\n    else\r\n    {\r\n        std::cout << \"still: \" << \"pointer is invalid\" << std::endl;\r\n    }\r\n}\r\n\r\n\r\nvoid mytest()\r\n{\r\n    std::shared_ptr<int> sp1(new int(22));\r\n    std::shared_ptr<int> sp2 = sp1;\r\n    std::weak_ptr<int> wp = sp1; \/\/ \u6307\u5411shared_ptr<int>\u6240\u6307\u5bf9\u8c61\r\n\r\n    std::cout << \"count: \" << wp.use_count() << std::endl; \/\/ count: 2\r\n    std::cout << *sp1 << std::endl; \/\/ 22\r\n    std::cout << *sp2 << std::endl; \/\/ 22\r\n    check(wp); \/\/ still: 22\r\n    \r\n    sp1.reset();\r\n    std::cout << \"count: \" << wp.use_count() << std::endl; \/\/ count: 1\r\n    std::cout << *sp2 << std::endl; \/\/ 22\r\n    check(wp); \/\/ still: 22\r\n\r\n    sp2.reset();\r\n    std::cout << \"count: \" << wp.use_count() << std::endl; \/\/ count: 0\r\n    check(wp); \/\/ still: pointer is invalid\r\n\r\n    return;\r\n}\r\n\r\nint main()\r\n{\r\n    mytest();\r\n\r\n    system(\"pause\");\r\n    return 0;\r\n}<\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
c++11 \u667a\u80fd\u6307\u9488 unique_pt<\/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":[],"tags":[118],"class_list":["post-1337","post","type-post","status-publish","format-standard","hentry","tag-02-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/1337","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=1337"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/1337\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=1337"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=1337"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=1337"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}