{"id":389,"date":"2020-04-05T21:51:34","date_gmt":"2020-04-05T13:51:34","guid":{"rendered":"https:\/\/www.notown.club\/?p=389"},"modified":"2023-05-29T09:51:14","modified_gmt":"2023-05-29T01:51:14","slug":"c-%e5%8a%a8%e6%80%81%e5%86%85%e5%ad%98%ef%bc%88%e7%ac%94%e8%ae%b0%e4%b8%80%ef%bc%89","status":"publish","type":"post","link":"https:\/\/www.notown.top\/?p=389","title":{"rendered":"C++ \u52a8\u6001\u5185\u5b58\uff08\u7b14\u8bb0\u4e00\uff09"},"content":{"rendered":"\n

\u9759\u6001\u5185\u5b58<\/strong>\u7528\u6765\u4fdd\u5b58\u5c40\u90e8static\u5bf9\u8c61\u3001\u7c7bstatic\u6570\u636e\u6210\u5458\u4ee5\u53ca\u5b9a\u4e49\u5728\u4efb\u4f55\u51fd\u6570\u4e4b\u5916\u7684\u53d8\u91cf\u3002\u6808\u5185\u5b58\u7528\u4e8e\u4fdd\u5b58\u5728\u51fd\u6570\u4f53\u5185\u7684\u975estatic\u5bf9\u8c61\u3002\u5206\u914d\u5728\u9759\u6001\u6216\u6808\u5185\u5b58\u4e2d\u7684\u5bf9\u8c61\u7531\u7f16\u8bd1\u5668\u81ea\u52a8\u521b\u5efa\u6216\u9500\u6bc1\u3002\u5bf9\u4e8e\u6808\u5bf9\u8c61\uff0c\u4ec5\u5728\u5176\u5b9a\u4e49\u7684\u7a0b\u5e8f\u5757\u8fd0\u884c\u65f6\u624d\u5b58\u5728\uff1bstatic\u5bf9\u8c61\u5728\u4f7f\u7528\u4e4b\u524d\u5206\u914d\uff0c\u5728\u7a0b\u5e8f\u7ed3\u675f\u65f6\u9500\u6bc1
\u9664\u4e86\u9759\u6001\u5185\u5b58\u548c\u6808\u5185\u5b58\uff0c\u6bcf\u4e2a\u7a0b\u5e8f\u8fd8\u62e5\u6709\u4e00\u4e2a\u5185\u5b58\u6c60\u3002\u8fd9\u90e8\u5206\u5185\u5b58\u88ab\u79f0\u4f5c\u81ea\u7531\u7a7a\u95f4\u6216\u5806\u3002\u7a0b\u5e8f\u7528\u5806\u6765\u5b58\u50a8\u52a8\u6001\u5206\u914d\u7684\u5bf9\u8c61\u2014\uff08\u90a3\u4e9b\u5728\u7a0b\u5e8f\u8fd0\u884c\u65f6\u5206\u914d\u7684\u5bf9\u8c61\uff09\u3002\u52a8\u6001\u5bf9\u8c61\u7684\u751f\u5b58\u671f\u7531\u7a0b\u5e8f\u6765\u63a7\u5236\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u5f53\u52a8\u6001\u5bf9\u8c61\u4e0d\u518d\u4f7f\u7528\u65f6\uff0c\u6211\u4eec\u7684\u4ee3\u7801\u5fc5\u987b\u663e\u793a\u5730\u9500\u6bc1\u5b83\u3002<\/p>\n\n\n\n

\u5728c++\u4e2d\uff0c\u52a8\u6001\u5185\u5b58\u7684\u7ba1\u7406\u662f\u901a\u8fc7\u4e00\u5bf9\u8fd0\u7b97\u7b26\u6765\u5b8c\u6210\u7684\uff1anew\uff0c\u5728\u52a8\u6001\u5185\u5b58\u4e2d\u4e3a\u5bf9\u8c61\u5206\u914d\u7a7a\u95f4\u5e76\u8fd4\u56de\u4e00\u4e2a\u6307\u5411\u8be5\u5bf9\u8c61\u7684\u6307\u9488
delete\uff0c\u63a5\u53d7\u4e00\u4e2a\u52a8\u6001\u5bf9\u8c61\u7684\u6307\u9488\uff0c\u5e76\u9500\u6bc1\u8be5\u5bf9\u8c61\uff0c\u91ca\u653e\u4e0e\u4e4b\u5173\u8054\u7684\u5185\u5b58\u3002<\/p>\n\n\n\n

\u65b0\u7684\u6807\u51c6\u5e93\u63d0\u4f9b\u4e86\u4e24\u79cd\u667a\u80fd\u6307\u9488\u7c7b\u578b\u6765\u7ba1\u7406\u52a8\u6001\u5bf9\u8c61\u3002\u667a\u80fd\u6307\u9488\u7684\u884c\u4e3a\u7c7b\u4f3c\u5e38\u89c4\u6307\u9488\uff0c\u91cd\u8981\u7684\u533a\u522b\u662f\u5b83\u8d1f\u8d23\u81ea\u52a8\u91ca\u653e\u6240\u6307\u5411\u7684\u5bf9\u8c61\uff08\u7279\u522b\u6ce8\u610f\u7684\u662f\u6709\u4e00\u79cd\u60c5\u51b5\uff0c\u5982\u679c\u662f\u81ea\u5df1new\u7684\u6307\u9488\uff0c\u5728delete\u4e4b\u524d\u4ee3\u7801\u629b\u51fa\u4e86\u5f02\u5e38\uff0c\u5219\u8fd9\u4e2a\u65f6\u5019\u5185\u5b58\u5e76\u4e0d\u4f1a\u88ab\u91ca\u653e\uff1b\u800c\u5bf9\u4e8e\u667a\u80fd\u6307\u9488\uff0c\u5b83\u8fd8\u662f\u80fd\u591f\u81ea\u52a8\u91ca\u653e\uff09<\/strong>\u3002\u65b0\u6807\u51c6\u5e93\u63d0\u4f9b\u7684\u8fd9\u4e24\u79cd\u667a\u80fd\u6307\u9488\u7684\u533a\u522b\u5728\u4e8e\u7ba1\u7406\u5e95\u5c42\u6307\u9488\u7684\u65b9\u5f0f\uff1a
share_ptr \u5141\u8bb8\u591a\u4e2a\u6307\u9488\u6307\u5411\u540c\u4e00\u5bf9\u8c61\uff1b
unique_ptr\u5219\u201c\u72ec\u5360\u201d\u6240\u6307\u5411\u7684\u5bf9\u8c61\uff1b
\u6807\u51c6\u5e93\u8fd8\u5b9a\u4e49\u4e86\u4e00\u4e2a\u540d\u4e3aweak_ptr\u7684\u4f34\u968f\u7c7b\uff0c\u5b83\u662f\u4e00\u79cd\u5f31\u5f15\u7528\uff0c\u6307\u5411share_ptr\u6240\u7ba1\u7406\u7684\u5bf9\u8c61\u3002\u8fd9\u4e09\u79cd\u7c7b\u578b\u90fd\u5b9a\u4e49\u5728memory\u5934\u6587\u4ef6\u4e2d\u3002<\/p>\n\n\n\n

\u4e00\u3001shared_ptr\u7c7b<\/strong><\/p>\n\n\n\n

\u7c7b\u4f3cvector\uff0c\u667a\u80fd\u6307\u9488\u4e5f\u662f\u6a21\u677f\uff0c\u56e0\u6b64\u5f53\u6211\u521b\u5efa\u4e00\u4e2a\u667a\u80fd\u6307\u9488\u7684\u65f6\u5019\uff0c\u5fc5\u987b\u63d0\u4f9b\u4e00\u4e9b\u989d\u5916\u7684\u4fe1\u606f\uff08\u6307\u9488\u53ef\u4ee5\u6307\u5411\u7684\u7c7b\u578b\uff09\u3002\u4e0evector\u4e00\u6837\uff0c\u6211\u4eec\u5728\u5c16\u62ec\u53f7\u5185\u7ed9\u51fa\u7c7b\u578b\uff0c\u4e4b\u540e\u662f\u6240\u5b9a\u4e49\u7684\u8fd9\u79cd\u667a\u80fd\u6307\u9488\u7684\u540d\u5b57\u3002<\/p>\n\n\n\n

shared_ptr <string> p1; \/\/shared_ptr\u53ef\u4ee5\u6307\u5411string
shared_ptr <list<int>> p2; \/\/shared_ptr\u53ef\u4ee5\u6307\u5411int\u7684list<\/code>
\uff08\u9ed8\u8ba4\u521d\u59cb\u5316\u7684\u667a\u80fd\u6307\u9488\u4e2d\u4fdd\u5b58\u7740\u4e00\u4e2a\u7a7a\u6307\u9488\uff09<\/p>\n\n\n\n

\u667a\u80fd\u6307\u9488\u7684\u4f7f\u7528\u65b9\u5f0f\u4e0e\u666e\u901a\u6307\u9488\u7c7b\u4f3c\uff0c\u89e3\u5f15\u7528\u4e00\u4e2a\u667a\u80fd\u6307\u9488\uff0c\u80fd\u8fd4\u56de\u4e00\u4e2a\u5b83\u6307\u5411\u7684\u5bf9\u8c61
\u4f8b\u5b50\uff1a
if (p1 && p1->empty()) \/\/\u5982\u679cp1\u7684\u503c\u4e0d\u4e3a\u7a7a\uff0c\u68c0\u67e5\u4ed6\u662f\u5426\u6307\u5411\u4e00\u4e2a\u7a7astring
     *p1=\u201dhi\u201d ;     \/\/\u5982\u679cp1\u4e0d\u4e3a\u7a7a\uff0c\u8fd8\u6307\u5411\u4e00\u4e2a\u7a7astring\uff0c\u5c31\u8d4b\u4e00\u65b0\u503c\u7ed9\u5b83\u3002<\/code><\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

make_shared\u51fd\u6570<\/strong><\/p>\n\n\n\n

\u6700\u5b89\u5168\u7684\u5206\u914d\u4f7f\u7528\u52a8\u6001\u5185\u5b58\u7684\u65b9\u6cd5\u662f\u8c03\u7528\u4e00\u4e2a\u540d\u4e3amake_shared\u7684\u6807\u51c6\u5e93\u51fd\u6570\u3002\u8fd9\u4e2a\u51fd\u6570\u53ef\u4ee5\u5728\u52a8\u6001\u5185\u5b58\u4e2d\u5206\u914d\u4e00\u4e2a\u5bf9\u8c61\u5e76\u521d\u59cb\u5316\u5b83\uff0c\u8fd4\u56de\u6307\u5411\u6b64\u5bf9\u8c61\u7684share_ptr\u3002<\/p>\n\n\n\n

shared_ptr<int> pp1 = make_shared<int> (7);<\/code><\/p>\n\n\n\n

\u7531\u4e8e\u6700\u540e\u4e00\u4e2ashared_ptr\u9500\u6bc1\u4e4b\u524d\uff0c\u5185\u5b58\u90fd\u4e0d\u4f1a\u88ab\u91ca\u653e\uff0c\u56e0\u6b64\uff0c\u786e\u4fdd\u4e86\u67d0\u4e2ashare_ptr\u4e0d\u518d\u4f1a\u88ab\u4f7f\u7528\u7684\u8bdd\uff0c\u5e94\u8be5\u7528erase\u5220\u9664\u5b83\u3002<\/p>\n\n\n\n

\u7a0b\u5e8f\u4f7f\u7528\u52a8\u6001\u5185\u5b58\u51fa\u4e8e\u4e00\u4e0b\u4e09\u79cd\u539f\u56e0\u4e4b\u4e00\uff1a
1\u3001\u7a0b\u5e8f\u4e0d\u77e5\u9053\u81ea\u5df1\u9700\u8981\u4f7f\u7528\u591a\u5c11\u5bf9\u8c61.
2\u3001\u7a0b\u5e8f\u4e0d\u77e5\u9053\u6240\u9700\u5bf9\u8c61\u7684\u51c6\u786e\u7c7b\u578b\u3002
3\u3001\u7a0b\u5e8f\u9700\u8981\u5728\u591a\u4e2a\u5bf9\u8c61\u95f4\u5171\u4eab\u6570\u636e\u3002<\/p>\n\n\n\n

\u4e8c\u3001unique_ptr\u7c7b<\/strong><\/p>\n\n\n\n

\u4e0eshare_ptr\u4e0d\u540c\uff0c\u4efb\u610f\u65f6\u523b\u53ea\u80fd\u6709\u4e00\u4e2aunique_ptr\u6307\u5411\u7ed9\u5b9a\u7684\u5bf9\u8c61\uff0c\u5f53unique_ptr\u88ab\u9500\u6bc1\u65f6\uff0c\u5b83\u6240\u6307\u5411\u7684\u5bf9\u8c61\u4e5f\u88ab\u9500\u6bc1\u3002
\u4e0e\u4e0eshare_ptr\u4e0d\u540c\uff0c\u6ca1\u6709\u7c7b\u4f3cmake_shared\u7684\u6807\u51c6\u5e93\u51fd\u6570\u8fd4\u56de\u4e00\u4e2aunique_ptr\u3002\u6211\u4eec\u5b9a\u4e49\u4e00\u4e2aunique_ptr\u65f6\uff0c\u9700\u8981\u5c06\u4ed6\u7ed1\u5b9a\u5230\u4e00\u4e2anew\u8fd4\u56de\u7684\u6307\u9488\u3002\u521d\u59cb\u5316\u65f6\uff0c\u5fc5\u987b\u91c7\u7528\u76f4\u63a5\u521d\u59cb\u5316\u3002<\/p>\n\n\n\n

unique_ptr<double> p1;\/\/\u53ef\u4ee5\u6307\u5411\u4e00\u4e2adouble\u7684unique_ptr
unique_ptr<int> p2(new int (42));\/\/p2\u6307\u5411\u4e00\u4e2a\u503c\u4e3a42\u7684int<\/code><\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

get\u7528\u6765\u5c06\u6307\u9488\u7684\u8bbf\u95ee\u6743\u9650\u4f20\u9012\u7ed9\u4ee3\u7801\uff0c\u53ea\u6709\u5728\u786e\u5b9a\u4ee3\u7801\u4e0d\u4f1adelete\u6307\u9488\u7684\u60c5\u51b5\u4e0b\uff0c\u624d\u80fd\u4f7f\u7528get\u3002\u7279\u522b\u662f\uff0c\u6c38\u8fdc\u4e0d\u8981\u7528get\u521d\u59cb\u5316\u53e6\u4e00\u4e2a\u667a\u80fd\u6307\u9488\u6216\u8005\u4e3a\u53e6\u4e00\u4e2a\u667a\u80fd\u6307\u9488\u8d4b\u503c\u3002<\/strong><\/p>\n\n\n\n

\u7528\u667a\u80fd\u6307\u9488\u65f6\uff0c\u5fc5\u987b\u9075\u5b88\uff1a
1\u3001\u4e0d\u4f7f\u7528\u76f8\u540c\u7684\u5185\u7f6e\u6307\u9488\u503c\u521d\u59cb\u5316\uff08\u6216reset\uff09\u591a\u4e2a\u667a\u80fd\u6307\u9488
2\u3001\u4e0ddelete get()\u8fd4\u56de\u7684\u6307\u9488
3\u3001\u4e0d\u9002\u7528get()\u521d\u59cb\u5316\u6216reset\u53e6\u4e00\u4e2a\u667a\u80fd\u6307\u9488\u3002
4\u3001\u5982\u679c\u4f60\u4f7f\u7528get()\u8fd4\u56de\u7684\u6307\u9488\uff0c\u8bb0\u4f4f\u5f53\u6700\u540e\u4e00\u4e2a\u5bf9\u5e94\u7684\u6307\u9488\u6307\u9488\u9500\u6bc1\u540e\uff0c\u4f60\u5bf9\u5e94\u7684\u6307\u9488\u5c31\u53d8\u4e3a\u65e0\u6548\u4e86
5\u3001\u5982\u679c\u4f60\u4f7f\u7528\u667a\u80fd\u6307\u9488\u7ba1\u7406\u7684\u8d44\u6e90\u4e0d\u662fnew\u5206\u914d\u7684\u5185\u5b58\uff0c\u8bb0\u4f4f\u4f20\u9012\u7ed9\u5b83\u4e00\u4e2a\u5220\u9664\u5668\u3002<\/p>\n\n\n\n

\u4e09\u3001weak_ptr\u7c7b<\/strong><\/p>\n\n\n\n

weak_ptr\u662f\u4e00\u79cd\u4e0d\u63a7\u5236\u6240\u6307\u5411\u5bf9\u8c61\u751f\u5b58\u671f\u7684\u667a\u80fd\u6307\u9488\uff0c\u5b83\u6307\u5411\u7531\u4e00\u4e2ashare_ptr\u7ba1\u7406\u7684\u5bf9\u8c61\u3002\u5c06weak_ptr\u7ed1\u5b9a\u5230\u4e00\u4e2ashared_ptr\u4e0d\u4f1a\u6539\u53d8share_ptr\u7684\u5f15\u7528\u6b21\u6570\u3002\u4e00\u65e6\u6700\u540e\u4e00\u4e2a\u6307\u5411\u5bf9\u8c61\u7684shared_ptr\u88ab\u9500\u6bc1\uff0c\u5bf9\u8c61\u5c31\u4f1a\u88ab\u91ca\u653e\u3002\u5373\u4f7f\u6709weak_ptr\u6307\u5411\u5bf9\u8c61\uff0c\u5bf9\u8c61\u4e5f\u8fd8\u662f\u4f1a\u88ab\u91ca\u653e\uff0c\u56e0\u6b64\uff0cweak_ptr\u7684\u540d\u5b57\u6293\u4f4f\u4e86\u8fd9\u79cd\u667a\u80fd\u6307\u9488”\u5f31”\u5171\u4eab\u5bf9\u8c61\u7684\u7279\u70b9\u3002 <\/p>\n\n\n\n

\n
\"\"<\/figure>\n<\/figure>\n\n\n\n
shared_ptr p1 = make_shared(65);\n     weak_ptr p2(p1);\n     \/\/p1.reset();\n     if (shared_ptr np = p2.lock())\n     {\n         cout << *np << endl;\n     }\n     else\n     {\n         cout << \"\u7528\u4e0d\u4e86\u8bf6\" << endl;\n     }<\/pre>\n\n\n\n
\u7531\u4e8e\u5bf9\u8c61\u53ef\u80fd\u4e0d\u5b58\u5728\uff0c\u4e0d\u80fd\u76f4\u63a5\u4f7f\u7528weak_ptr\u8bbf\u95ee\u5bf9\u8c61\uff0c\u800c\u5fc5\u987b\u8c03\u7528lock\u3002\u6b64\u51fd\u6570\u4f1a\u68c0\u67e5weak_ptr\u6307\u5411\u7684\u5bf9\u8c61\u662f\u5426\u4ecd\u7136\u5b58\u5728\u3002\u5982\u679c\u5b58\u5728\u5219\u8fd4\u56de\u4e00\u4e2a\u6307\u5411\u5171\u4eab\u5bf9\u8c61\u7684share_ptr\u3002<\/p>\n\n\n\n
\u56db\u3001C++\u5185\u5b58\u6a21\u578b<\/strong><\/p>\n\n\n\n
C++\u5185\u5b58\u6a21\u578b\u53ef\u5206\u4e3a\u56db\u4e2a\u90e8\u5206\uff0c\u4ee3\u7801\u533a\u3001\u5168\u5c40\u533a\u3001\u6808\u533a\u3001\u5806\u533a
\u4ee3\u7801\u533a\uff1a\u4fdd\u5b58\u51fd\u6570\u4f53\u7684\u4e8c\u8fdb\u5236\u4ee3\u7801\uff0c\u7531\u64cd\u4f5c\u7cfb\u7edf\u7ba1\u7406
\u5168\u5c40\u533a\uff1a\u4fdd\u5b58\u5168\u5c40\u53d8\u91cf\u3001\u9759\u6001\u53d8\u91cf\u3001\u5e38\u91cf\uff0c\u5728\u7a0b\u5e8f\u8fd0\u884c\u5468\u671f\u4e00\u76f4\u5b58\u5728
\u6808\u533a\uff1a\u4fdd\u5b58\u51fd\u6570\u7684\u5c40\u90e8\u53d8\u91cf\uff0c\u5f62\u53c2\u7b49\uff0c\u7531\u7f16\u8bd1\u5668\u53bb\u8fdb\u884c\u6570\u636e\u7684\u4fdd\u5b58\u548c\u91ca\u653e
\u5806\u533a\uff1a\u7a0b\u5e8f\u5458\u81ea\u7531\u7533\u8bf7\u91ca\u653e\u7684\u5185\u5b58\u7a7a\u95f4\uff0c\u5982\u679c\u5fd8\u8bb0\u91ca\u653e\uff0c\u5c06\u5728\u7a0b\u5e8f\u8fd0\u884c\u7ed3\u675f\u540e\u7531\u7cfb\u7edf\u56de\u6536<\/p>\n","protected":false},"excerpt":{"rendered":"
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