“`” C++\u91cc\u9762\u7684\u56db\u4e2a\u667a\u80fd\u6307\u9488: auto_ptr, shared_ptr, weak_ptr, unique_ptr \u5176\u4e2d\u540e\u4e09\u4e2a\u662fc++11\u652f\u6301\uff0c\u5e76\u4e14\u7b2c\u4e00\u4e2a\u5df2\u7ecf\u88ab11\u5f03\u7528\u3002<\/p>\n
\u4e3a\u4ec0\u4e48\u8981\u4f7f\u7528\u667a\u80fd\u6307\u9488\uff1a<\/p>\n
\u667a\u80fd\u6307\u9488\u7684\u4f5c\u7528\u662f\u7ba1\u7406\u4e00\u4e2a\u6307\u9488\uff0c\u56e0\u4e3a\u5b58\u5728\u4ee5\u4e0b\u8fd9\u79cd\u60c5\u51b5\uff1a\u7533\u8bf7\u7684\u7a7a\u95f4\u5728\u51fd\u6570\u7ed3\u675f\u65f6\u5fd8\u8bb0\u91ca\u653e\uff0c\u9020\u6210\u5185\u5b58\u6cc4\u6f0f\u3002\u4f7f\u7528\u667a\u80fd\u6307\u9488\u53ef\u4ee5\u5f88\u5927\u7a0b\u5ea6\u4e0a\u7684\u907f\u514d\u8fd9\u4e2a\u95ee\u9898\uff0c\u56e0\u4e3a\u667a\u80fd\u6307\u9488\u5c31\u662f\u4e00\u4e2a\u7c7b\uff0c\u5f53\u8d85\u51fa\u4e86\u7c7b\u7684\u4f5c\u7528\u57df\u662f\uff0c\u7c7b\u4f1a\u81ea\u52a8\u8c03\u7528\u6790\u6784\u51fd\u6570\uff0c\u6790\u6784\u51fd\u6570\u4f1a\u81ea\u52a8\u91ca\u653e\u8d44\u6e90\u3002\u6240\u4ee5\u667a\u80fd\u6307\u9488\u7684\u4f5c\u7528\u539f\u7406\u5c31\u662f\u5728\u51fd\u6570\u7ed3\u675f\u65f6\u81ea\u52a8\u91ca\u653e\u5185\u5b58\u7a7a\u95f4\uff0c\u4e0d\u9700\u8981\u624b\u52a8\u91ca\u653e\u5185\u5b58\u7a7a\u95f4\u3002<\/p>\n
\u91c7\u7528\u6240\u6709\u6743\u6a21\u5f0f\u3002<\/p>\n<\/p>\n<\/li>\n<\/ol>\n
auto_ptr< string> p1 (new string (\"\"I reigned lonely as a cloud.\u201d)); auto_ptr<string> p2; p2 = p1; \/\/auto_ptr\u4e0d\u4f1a\u62a5\u9519.<\/code><\/pre>\n \u6b64\u65f6\u4e0d\u4f1a\u62a5\u9519\uff0cp2\u5265\u593a\u4e86p1\u7684\u6240\u6709\u6743\uff0c\u4f46\u662f\u5f53\u7a0b\u5e8f\u8fd0\u884c\u65f6\u8bbf\u95eep1\u5c06\u4f1a\u62a5\u9519\u3002\u6240\u4ee5auto_ptr\u7684\u7f3a\u70b9\u662f\uff1a\u5b58\u5728\u6f5c\u5728\u7684\u5185\u5b58\u5d29\u6e83\u95ee\u9898\uff01<\/p>\n
2. unique_ptr\uff08\u66ff\u6362auto_ptr\uff09<\/p>\n
unique_ptr\u5b9e\u73b0\u72ec\u5360\u5f0f\u62e5\u6709\u6216\u4e25\u683c\u62e5\u6709\u6982\u5ff5\uff0c\u4fdd\u8bc1\u540c\u4e00\u65f6\u95f4\u5185\u53ea\u6709\u4e00\u4e2a\u667a\u80fd\u6307\u9488\u53ef\u4ee5\u6307\u5411\u8be5\u5bf9\u8c61\u3002\u5b83\u5bf9\u4e8e\u907f\u514d\u8d44\u6e90\u6cc4\u9732(\u4f8b\u5982\u201c\u4ee5new\u521b\u5efa\u5bf9\u8c61\u540e\u56e0\u4e3a\u53d1\u751f\u5f02\u5e38\u800c\u5fd8\u8bb0\u8c03\u7528delete\u201d)\u7279\u522b\u6709\u7528\u3002<\/p>\n
\u91c7\u7528\u6240\u6709\u6743\u6a21\u5f0f\uff0c\u8fd8\u662f\u4e0a\u9762\u90a3\u4e2a\u4f8b\u5b50<\/p>\n
`unique_ptr p3 (new` `string (\"\"auto\"\")); \/\/#4unique_ptr p4\uff1b \/\/#5p4 = p3;\/\/\u6b64\u65f6\u4f1a\u62a5\u9519\uff01\uff01`<\/code><\/pre>\n \u7f16\u8bd1\u5668\u8ba4\u4e3ap4=p3\u975e\u6cd5\uff0c\u907f\u514d\u4e86p3\u4e0d\u518d\u6307\u5411\u6709\u6548\u6570\u636e\u7684\u95ee\u9898\u3002\u56e0\u6b64\uff0cunique_ptr\u6bd4auto_ptr\u66f4\u5b89\u5168\u3002<\/p>\n
\u53e6\u5916unique_ptr\u8fd8\u6709\u66f4\u806a\u660e\u7684\u5730\u65b9\uff1a\u5f53\u7a0b\u5e8f\u8bd5\u56fe\u5c06\u4e00\u4e2a unique_ptr \u8d4b\u503c\u7ed9\u53e6\u4e00\u4e2a\u65f6\uff0c\u5982\u679c\u6e90 unique_ptr \u662f\u4e2a\u4e34\u65f6\u53f3\u503c\uff0c\u7f16\u8bd1\u5668\u5141\u8bb8\u8fd9\u4e48\u505a\uff1b\u5982\u679c\u6e90 unique_ptr \u5c06\u5b58\u5728\u4e00\u6bb5\u65f6\u95f4\uff0c\u7f16\u8bd1\u5668\u5c06\u7981\u6b62\u8fd9\u4e48\u505a\uff0c\u6bd4\u5982\uff1a<\/p>\n
unique_ptr<string> pu1(new string (\"\"hello world\"\")); unique_ptr<string> pu2; pu2 = pu1; \/\/ #1 not allowed unique_ptr<string> pu3; pu3 = unique_ptr<string>(new string (\"\"You\"\")); \/\/ #2 allowed<\/code><\/pre>\n \u5176\u4e2d#1\u7559\u4e0b\u60ac\u6302\u7684unique_ptr(pu1)\uff0c\u8fd9\u53ef\u80fd\u5bfc\u81f4\u5371\u5bb3\u3002\u800c#2\u4e0d\u4f1a\u7559\u4e0b\u60ac\u6302\u7684unique_ptr\uff0c\u56e0\u4e3a\u5b83\u8c03\u7528 unique_ptr \u7684\u6784\u9020\u51fd\u6570\uff0c\u8be5\u6784\u9020\u51fd\u6570\u521b\u5efa\u7684\u4e34\u65f6\u5bf9\u8c61\u5728\u5176\u6240\u6709\u6743\u8ba9\u7ed9 pu3 \u540e\u5c31\u4f1a\u88ab\u9500\u6bc1\u3002\u8fd9\u79cd\u968f\u60c5\u51b5\u800c\u5df2\u7684\u884c\u4e3a\u8868\u660e\uff0cunique_ptr \u4f18\u4e8e\u5141\u8bb8\u4e24\u79cd\u8d4b\u503c\u7684auto_ptr \u3002<\/p>\n
\u6ce8\uff1a\u5982\u679c\u786e\u5b9e\u60f3\u6267\u884c\u7c7b\u4f3c\u4e0e#1\u7684\u64cd\u4f5c\uff0c\u8981\u5b89\u5168\u7684\u91cd\u7528\u8fd9\u79cd\u6307\u9488\uff0c\u53ef\u7ed9\u5b83\u8d4b\u65b0\u503c\u3002C++\u6709\u4e00\u4e2a\u6807\u51c6\u5e93\u51fd\u6570std::move()\uff0c\u8ba9\u4f60\u80fd\u591f\u5c06\u4e00\u4e2aunique_ptr\u8d4b\u7ed9\u53e6\u4e00\u4e2a\u3002\u4f8b\u5982\uff1a<\/p>\n
unique_ptr<string> ps1, ps2; ps1 = demo(\"\"hello\"\"); ps2 = move(ps1); ps1 = demo(\"\"alexia\"\"); cout << *ps2 << *ps1 << endl;<\/code><\/pre>\n 3. shared_ptr<\/p>\n
shared_ptr\u5b9e\u73b0\u5171\u4eab\u5f0f\u62e5\u6709\u6982\u5ff5\u3002\u591a\u4e2a\u667a\u80fd\u6307\u9488\u53ef\u4ee5\u6307\u5411\u76f8\u540c\u5bf9\u8c61\uff0c\u8be5\u5bf9\u8c61\u548c\u5176\u76f8\u5173\u8d44\u6e90\u4f1a\u5728\u201c\u6700\u540e\u4e00\u4e2a\u5f15\u7528\u88ab\u9500\u6bc1\u201d\u65f6\u5019\u91ca\u653e\u3002\u4ece\u540d\u5b57share\u5c31\u53ef\u4ee5\u770b\u51fa\u4e86\u8d44\u6e90\u53ef\u4ee5\u88ab\u591a\u4e2a\u6307\u9488\u5171\u4eab\uff0c\u5b83\u4f7f\u7528\u8ba1\u6570\u673a\u5236\u6765\u8868\u660e\u8d44\u6e90\u88ab\u51e0\u4e2a\u6307\u9488\u5171\u4eab\u3002\u53ef\u4ee5\u901a\u8fc7\u6210\u5458\u51fd\u6570use_count()\u6765\u67e5\u770b\u8d44\u6e90\u7684\u6240\u6709\u8005\u4e2a\u6570\u3002\u9664\u4e86\u53ef\u4ee5\u901a\u8fc7new\u6765\u6784\u9020\uff0c\u8fd8\u53ef\u4ee5\u901a\u8fc7\u4f20\u5165auto_ptr, unique_ptr,weak_ptr\u6765\u6784\u9020\u3002\u5f53\u6211\u4eec\u8c03\u7528release()\u65f6\uff0c\u5f53\u524d\u6307\u9488\u4f1a\u91ca\u653e\u8d44\u6e90\u6240\u6709\u6743\uff0c\u8ba1\u6570\u51cf\u4e00\u3002\u5f53\u8ba1\u6570\u7b49\u4e8e0\u65f6\uff0c\u8d44\u6e90\u4f1a\u88ab\u91ca\u653e\u3002<\/p>\n
shared_ptr \u662f\u4e3a\u4e86\u89e3\u51b3 auto_ptr \u5728\u5bf9\u8c61\u6240\u6709\u6743\u4e0a\u7684\u5c40\u9650\u6027(auto_ptr \u662f\u72ec\u5360\u7684), \u5728\u4f7f\u7528\u5f15\u7528\u8ba1\u6570\u7684\u673a\u5236\u4e0a\u63d0\u4f9b\u4e86\u53ef\u4ee5\u5171\u4eab\u6240\u6709\u6743\u7684\u667a\u80fd\u6307\u9488\u3002<\/p>\n
\u6210\u5458\u51fd\u6570\uff1a<\/p>\n
use_count \u8fd4\u56de\u5f15\u7528\u8ba1\u6570\u7684\u4e2a\u6570<\/p>\n
unique \u8fd4\u56de\u662f\u5426\u662f\u72ec\u5360\u6240\u6709\u6743( use_count \u4e3a 1)<\/p>\n
swap \u4ea4\u6362\u4e24\u4e2a shared_ptr \u5bf9\u8c61(\u5373\u4ea4\u6362\u6240\u62e5\u6709\u7684\u5bf9\u8c61)<\/p>\n
reset \u653e\u5f03\u5185\u90e8\u5bf9\u8c61\u7684\u6240\u6709\u6743\u6216\u62e5\u6709\u5bf9\u8c61\u7684\u53d8\u66f4, \u4f1a\u5f15\u8d77\u539f\u6709\u5bf9\u8c61\u7684\u5f15\u7528\u8ba1\u6570\u7684\u51cf\u5c11<\/p>\n
get \u8fd4\u56de\u5185\u90e8\u5bf9\u8c61(\u6307\u9488), \u7531\u4e8e\u5df2\u7ecf\u91cd\u8f7d\u4e86()\u65b9\u6cd5, \u56e0\u6b64\u548c\u76f4\u63a5\u4f7f\u7528\u5bf9\u8c61\u662f\u4e00\u6837\u7684.\u5982 shared_ptr sp(new int(1)); sp \u4e0e sp.get()\u662f\u7b49\u4ef7\u7684<\/int><\/p>\n 4. weak_ptr<\/p>\n
weak_ptr \u662f\u4e00\u79cd\u4e0d\u63a7\u5236\u5bf9\u8c61\u751f\u547d\u5468\u671f\u7684\u667a\u80fd\u6307\u9488, \u5b83\u6307\u5411\u4e00\u4e2a shared_ptr \u7ba1\u7406\u7684\u5bf9\u8c61. \u8fdb\u884c\u8be5\u5bf9\u8c61\u7684\u5185\u5b58\u7ba1\u7406\u7684\u662f\u90a3\u4e2a\u5f3a\u5f15\u7528\u7684 shared_ptr. weak_ptr\u53ea\u662f\u63d0\u4f9b\u4e86\u5bf9\u7ba1\u7406\u5bf9\u8c61\u7684\u4e00\u4e2a\u8bbf\u95ee\u624b\u6bb5\u3002weak_ptr \u8bbe\u8ba1\u7684\u76ee\u7684\u662f\u4e3a\u914d\u5408 shared_ptr \u800c\u5f15\u5165\u7684\u4e00\u79cd\u667a\u80fd\u6307\u9488\u6765\u534f\u52a9 shared_ptr \u5de5\u4f5c, \u5b83\u53ea\u53ef\u4ee5\u4ece\u4e00\u4e2a shared_ptr \u6216\u53e6\u4e00\u4e2a weak_ptr \u5bf9\u8c61\u6784\u9020, \u5b83\u7684\u6784\u9020\u548c\u6790\u6784\u4e0d\u4f1a\u5f15\u8d77\u5f15\u7528\u8bb0\u6570\u7684\u589e\u52a0\u6216\u51cf\u5c11\u3002weak_ptr\u662f\u7528\u6765\u89e3\u51b3shared_ptr\u76f8\u4e92\u5f15\u7528\u65f6\u7684\u6b7b\u9501\u95ee\u9898,\u5982\u679c\u8bf4\u4e24\u4e2ashared_ptr\u76f8\u4e92\u5f15\u7528,\u90a3\u4e48\u8fd9\u4e24\u4e2a\u6307\u9488\u7684\u5f15\u7528\u8ba1\u6570\u6c38\u8fdc\u4e0d\u53ef\u80fd\u4e0b\u964d\u4e3a0,\u8d44\u6e90\u6c38\u8fdc\u4e0d\u4f1a\u91ca\u653e\u3002\u5b83\u662f\u5bf9\u5bf9\u8c61\u7684\u4e00\u79cd\u5f31\u5f15\u7528\uff0c\u4e0d\u4f1a\u589e\u52a0\u5bf9\u8c61\u7684\u5f15\u7528\u8ba1\u6570\uff0c\u548cshared_ptr\u4e4b\u95f4\u53ef\u4ee5\u76f8\u4e92\u8f6c\u5316\uff0cshared_ptr\u53ef\u4ee5\u76f4\u63a5\u8d4b\u503c\u7ed9\u5b83\uff0c\u5b83\u53ef\u4ee5\u901a\u8fc7\u8c03\u7528lock\u51fd\u6570\u6765\u83b7\u5f97shared_ptr\u3002<\/p>\n
class B; class A { public: shared_ptr<B> pb_; ~A() { cout<<\"\"A delete\\n\"\"; } }; class B { public: shared_ptr<A> pa_; ~B() { cout<<\"\"B delete\\n\"\"; } }; void fun() { shared_ptr<B> pb(new B()); shared_ptr<A> pa(new A()); pb->pa_ = pa; pa->pb_ = pb; cout<<pb.use_count()<<endl; cout<<pa.use_count()<<endl; } int main() { fun(); return 0; }<\/code><\/pre>\n \u53ef\u4ee5\u770b\u5230fun\u51fd\u6570\u4e2dpa \uff0cpb\u4e4b\u95f4\u4e92\u76f8\u5f15\u7528\uff0c\u4e24\u4e2a\u8d44\u6e90\u7684\u5f15\u7528\u8ba1\u6570\u4e3a2\uff0c\u5f53\u8981\u8df3\u51fa\u51fd\u6570\u65f6\uff0c\u667a\u80fd\u6307\u9488pa\uff0cpb\u6790\u6784\u65f6\u4e24\u4e2a\u8d44\u6e90\u5f15\u7528\u8ba1\u6570\u4f1a\u51cf\u4e00\uff0c\u4f46\u662f\u4e24\u8005\u5f15\u7528\u8ba1\u6570\u8fd8\u662f\u4e3a1\uff0c\u5bfc\u81f4\u8df3\u51fa\u51fd\u6570\u65f6\u8d44\u6e90\u6ca1\u6709\u88ab\u91ca\u653e\uff08A B\u7684\u6790\u6784\u51fd\u6570\u6ca1\u6709\u88ab\u8c03\u7528\uff09\uff0c\u5982\u679c\u628a\u5176\u4e2d\u4e00\u4e2a\u6539\u4e3aweak_ptr\u5c31\u53ef\u4ee5\u4e86\uff0c\u6211\u4eec\u628a\u7c7bA\u91cc\u9762\u7684shared_ptr pb; \u6539\u4e3aweak_ptr pb<\/em>; \u8fd0\u884c\u7ed3\u679c\u5982\u4e0b\uff0c\u8fd9\u6837\u7684\u8bdd\uff0c\u8d44\u6e90B\u7684\u5f15\u7528\u5f00\u59cb\u5c31\u53ea\u67091\uff0c\u5f53pb\u6790\u6784\u65f6\uff0cB\u7684\u8ba1\u6570\u53d8\u4e3a0\uff0cB\u5f97\u5230\u91ca\u653e\uff0cB\u91ca\u653e\u7684\u540c\u65f6\u4e5f\u4f1a\u4f7fA\u7684\u8ba1\u6570\u51cf\u4e00\uff0c\u540c\u65f6pa\u6790\u6784\u65f6\u4f7fA\u7684\u8ba1\u6570\u51cf\u4e00\uff0c\u90a3\u4e48A\u7684\u8ba1\u6570\u4e3a0\uff0cA\u5f97\u5230\u91ca\u653e\u3002<\/p>\n \u6ce8\u610f\u7684\u662f\u6211\u4eec\u4e0d\u80fd\u901a\u8fc7weak_ptr\u76f4\u63a5\u8bbf\u95ee\u5bf9\u8c61\u7684\u65b9\u6cd5\uff0c\u6bd4\u5982B\u5bf9\u8c61\u4e2d\u6709\u4e00\u4e2a\u65b9\u6cd5print(),\u6211\u4eec\u4e0d\u80fd\u8fd9\u6837\u8bbf\u95ee\uff0cpa->pb->print(); \u82f1\u6587pb<\/em>\u662f\u4e00\u4e2aweak_ptr\uff0c\u5e94\u8be5\u5148\u628a\u5b83\u8f6c\u5316\u4e3ashared_ptr,\u5982\uff1ashared_ptr p = pa->pb_.lock(); p->print();<\/p>\n \"```\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"“`” C++\u91cc\u9762\u7684\u56db\u4e2a\u667a\u80fd\u6307\u9488: auto_ptr, shared_ptr, wea […]<\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[101],"tags":[],"class_list":["post-39907","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/39907","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/comments?post=39907"}],"version-history":[{"count":1,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/39907\/revisions"}],"predecessor-version":[{"id":39908,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/posts\/39907\/revisions\/39908"}],"wp:attachment":[{"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/media?parent=39907"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/categories?post=39907"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/wx.kaifamiao.info\/index.php\/wp-json\/wp\/v2\/tags?post=39907"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}