{"id":4046,"date":"2019-12-25T10:57:39","date_gmt":"2019-12-25T02:57:39","guid":{"rendered":"https:\/\/damogame.cn\/wordpress\/?p=4046"},"modified":"2019-12-25T10:57:39","modified_gmt":"2019-12-25T02:57:39","slug":"stdcopy%e7%9a%84%e4%bd%bf%e7%94%a8","status":"publish","type":"post","link":"https:\/\/i007.cc\/wordpress\/archives\/4046","title":{"rendered":"std::copy\u7684\u4f7f\u7528"},"content":{"rendered":"

\u539f\u6587\u5730\u5740<\/a><\/p>\n

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\n
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\u770b\u5230\u6709\u4eba\u5728\u7528std::copy\u8fd9\u4e2a\u4e1c\u897f,\u5f88\u7b80\u6d01\u548c\u723d\u554a,,\u6240\u4ee5\u627e\u4e9b\u5e16\u5b50\u5b66\u4e60\u5b66\u4e60<\/p>\n

http:\/\/blog.sina.com.cn\/s\/blog_8655aeca0100t6qe.html<\/a><\/p>\n

https:\/\/www.so.com\/s?q=std%3A%3Acopy%E5%87%BD%E6%95%B0&ie=utf-8&src=se7_newtab_new<\/a><\/p>\n

 <\/p>\n

copy\u51fd\u6570\u7684\u51fd\u6570\u539f\u578b:<\/p>\n

\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n
1 \/\/fist [IN]: \u8981\u62f7\u8d1d\u5143\u7d20\u7684\u9996\u5730\u5740\r\n2 \/\/last [IN]:\u8981\u62f7\u8d1d\u5143\u7d20\u7684\u6700\u540e\u4e00\u4e2a\u5143\u7d20\u7684\u4e0b\u4e00\u4e2a\u5730\u5740\r\n3 \/\/x [OUT] : \u62f7\u8d1d\u7684\u76ee\u7684\u5730\u7684\u9996\u5730\u5740\r\n4 \r\n5 template<class InIt, class OutIt>\r\n6     OutIt copy(InIt first, InIt last, OutIt x);<\/pre>\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n<\/div>\n
 <\/p>\n
\u5982\u679c\u8981\u628a\u4e00\u4e2a\u5e8f\u5217\uff08sequence\uff09\u62f7\u8d1d\u5230\u4e00\u4e2a\u5bb9\u5668\uff08container\uff09\u4e2d\u53bb\uff0c\u901a\u5e38\u7528std::copy\u7b97\u6cd5\uff0c\u4ee3\u7801\u5982\u4e0b\uff1astd::copy(start, end, std::back_inserter(container));<\/strong><\/p>\n
\u00a0\u8fd9\u91cc\uff0cstart\u548cend\u662f\u8f93\u5165\u5e8f\u5217\uff08\u5047\u8bbe\u6709N\u5404\u5143\u7d20\uff09\u7684\u8fed\u4ee3\u5668\uff08iterator\uff09[\u4f8b\u5982start = iterator.begin(); end = iterator.end()]<\/sub>\uff0ccontainer\u662f\u4e00\u4e2a\u5bb9\u5668[\u4f8b\u5982vector]<\/sub>\uff0c\u8be5\u5bb9\u5668\u7684\u63a5\u53e3\u5305\u542b\u51fd\u6570push_back<\/strong>\u3002<\/p>\n
\u5047\u8bbecontainer\u5f00\u59cb\u662f\u7a7a\u7684\uff0c\u90a3\u4e48copy\u5b8c\u6bd5\u540e\u5b83\u5c31\u5305\u542bN\u4e2a\u5143\u7d20\uff0c\u5e76\u4e14\u987a\u5e8f\u4e0e\u539f\u6765\u961f\u5217\u4e2d\u7684\u5143\u7d20\u987a\u5e8f\u4e00\u6837\u3002\u6807\u51c6\u5e93\u63d0\u4f9b\u7684back_inserter\u6a21\u677f\u51fd\u6570\u5f88\u65b9\u4fbf\uff0c\u56e0\u4e3a\u5b83\u4e3acontainer\u8fd4\u56de\u4e00\u4e2aback_insert_iterator\u8fed\u4ee3\u5668\uff0c\u8fd9\u6837\uff0c\u590d\u5236\u7684\u5143\u7d20\u90fd\u88ab\u8ffd\u52a0\u5230container\u7684\u672b\u5c3e\u4e86\u3002<\/p>\n
\u73b0\u5728\u5047\u8bbecontainer\u5f00\u59cb\u975e\u7a7a\uff08\u4f8b\u5982\uff1acontainer\u5fc5\u987b\u5728\u5faa\u73af\u4e2d\u53cd\u590d\u88ab\u4f7f\u7528\u597d\u51e0\u6b21\uff09\u3002\u90a3\u4e48\uff0c\u8981\u8fbe\u5230\u539f\u6765\u7684\u76ee\u6807\uff0c\u5fc5\u987b\u5148\u8c03\u7528clear\u51fd\u6570\u7136\u540e\u624d\u80fd\u63d2\u5165\u65b0\u5e8f\u5217\u3002\u8fd9\u4f1a\u5bfc\u81f4\u65e7\u7684\u5143\u7d20\u5bf9\u8c61\u88ab\u6790\u6784\uff0c\u65b0\u6dfb\u52a0\u8fdb\u6765\u7684\u88ab\u6784\u9020\u3002\u4e0d\u4ec5\u5982\u6b64\uff0ccontainer\u81ea\u8eab\u4f7f\u7528\u7684\u52a8\u6001\u5185\u5b58\u4e5f\u4f1a\u88ab\u91ca\u653e\u7136\u540e\u53c8\u521b\u5efa\uff0c\u5c31\u50cflist\uff0cmap\uff0cset\u7684\u8282\u70b9\u3002\u67d0\u4e9bvector\u7684\u5b9e\u73b0\u5728\u8c03\u7528clear\u7684\u65f6\u5019\u751a\u81f3\u4f1a\u91ca\u653e\u6240\u6709\u5185\u5b58\u3002<\/p>\n
\n
\u901a\u5e38\uff0c\u8003\u8651\u5230\u5728\u4e00\u4e2a\u5df2\u6709\u7684\u5143\u7d20\u4e0a\u76f4\u63a5copy\u8986\u76d6\u66f4\u9ad8\u6548\u3002keyi\u8fd9\u6837\u505a\uff1a<\/p>\n
std::copy(start, end, container.begin());<\/p>\n
\u00a0\u5728\u8fd9\u91cc\u4f60\u5728container\u7684\u5934\u90e8\u6267\u884c\u4e86copy\uff0dover\uff08\u8986\u76d6\u8d4b\u503c\uff09\u64cd\u4f5c<\/strong>\uff0c\u4f46\u662f\uff0c\u5982\u679ccontainer\u7684\u5927\u5c0f\u5c0f\u4e8e\u8f93\u5165\u5e8f\u5217\u7684\u957f\u5ea6N\u7684\u8bdd\uff0c\u8fd9\u6bb5\u4ee3\u7801\u4f1a\u5bfc\u81f4\u5d29\u6e83\uff08crash\uff09<\/strong>\u3002<\/p>\n
eg1: \u00a0 \u00a0 \u00a0\u00a0\/\/\u53ef\u4ee5\u4f7f\u7528copy\u7ed9\u6570\u7ec4\u8d4b\u503c\u554a!!! \u00a0 \u4f46\u662f\u8981\u6ce8\u610f \u00a0sizeof(b) \u00a0\u5fc5\u987b\u5927\u4e8e \u00a0[(a+3) – (a)] \u7684\u957f\u5ea6<\/strong><\/p>\n
\u00a0\u00a0\u00a0int a[3]={1,2,3};<\/p>\n
\u00a0\u00a0\u00a0int b[3];
\nstd::copy(a,(a+3),b); \u00a0 ——>[a, a+3)
\nfor(int j=0;j<3;j++)
\ncout<<b[j]<\/strong><\/p>\n
eg2:<\/strong><\/p>\n
\u00a0\u00a0vector<int> temp(3); \u00a0\/\/\u521d\u59cb\u5316\u4e00\u4e2a\u67093\u4e2a\u5143\u7d20\u7684vector
\nint a[3]={1,2,3};<\/p>\n
\u00a0std::copy(a,a+3,&temp.front()); \u00a0 \/\/ \u6216\u8005\u662f \u00a0std::copy(a, a+3, temp.begin())\u4e5f\u53ef\u4ee5
\ncout<<<endl;
\nfor(int j=0;j < temp.size(); j++)
\ncout<<temp[j];
\ncopy\u53ea\u8d1f\u8d23\u590d\u5236\uff0c\u4e0d\u8d1f\u8d23\u7533\u8bf7\u7a7a\u95f4\uff0c\u6240\u4ee5\u590d\u5236\u524d\u5fc5\u987b\u6709\u8db3\u591f\u7684\u7a7a\u95f4<\/strong><\/p>\n
copy\u53ea\u8d1f\u8d23\u590d\u5236\uff0c\u4e0d\u8d1f\u8d23\u7533\u8bf7\u7a7a\u95f4\uff0c\u6240\u4ee5\u590d\u5236\u524d\u5fc5\u987b\u6709\u8db3\u591f\u7684\u7a7a\u95f4<\/strong><\/p>\n
copy\u53ea\u8d1f\u8d23\u590d\u5236\uff0c\u4e0d\u8d1f\u8d23\u7533\u8bf7\u7a7a\u95f4\uff0c\u6240\u4ee5\u590d\u5236\u524d\u5fc5\u987b\u6709\u8db3\u591f\u7684\u7a7a\u95f4<\/strong><\/p>\n
copy\u53ea\u8d1f\u8d23\u590d\u5236\uff0c\u4e0d\u8d1f\u8d23\u7533\u8bf7\u7a7a\u95f4\uff0c\u6240\u4ee5\u590d\u5236\u524d\u5fc5\u987b\u6709\u8db3\u591f\u7684\u7a7a\u95f4<\/strong><\/p>\n
\u00a0<\/strong><\/p>\n
\u63a5\u4e0b\u6765,\u8ba9\u6211\u4eec\u6765\u770b\u770b\u6570\u7ec4\u4e4b\u95f4\u76f4\u63a5\u7528for\u62f7\u8d1d\u548c\u7528copy\u62f7\u8d1d\u7684\u6548\u7387\u6bd4\u8f83\u00a0http:\/\/blog.csdn.net\/zhouxuguang236\/article\/details\/10834567<\/a><\/p>\n
\u5728C++\u7f16\u7a0b\u4e2d\uff0c\u7ecf\u5e38\u4f1a\u914d\u5230\u6570\u636e\u7684\u62f7\u8d1d\uff0c\u5982\u6570\u7ec4\u4e4b\u95f4\u5143\u7d20\u7684\u62f7\u8d1d\uff0c\u4e00\u822c\u7684\u4eba\u53ef\u80fd\u90fd\u4f1a\u7528for\u5faa\u73af\u9010\u4e2a\u5143\u7d20\u8fdb\u884c\u62f7\u8d1d\uff0c\u5728\u6570\u636e\u91cf\u4e0d\u5927\u7684\u60c5\u51b5\u4e0b\u8fd8\u53ef\u4ee5\uff0c\u5982\u679c\u6570\u636e\u91cf\u6bd4\u8f83\u5927\uff0c\u90a3\u4e48\u6548\u7387\u4f1a\u6bd4\u8f83\u5730\u4e0b\u3002\u800cSTL\u4e2d\u5c31\u63d0\u4f9b\u4e86\u4e00\u4e2a\u4e13\u95e8\u7528\u6765\u8fdb\u884c\u5bb9\u5668\u5143\u7d20\u62f7\u8d1d\u7684\u51fd\u6570copy<\/strong><\/p>\n
\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n
  1 #include<iostream>\r\n  2 #include<vector>\r\n  3 #include<sys\/time.h>\r\n  4 #include<time.h>\r\n  5 #include<iosfwd>\r\n  6 #include<algorithm>\r\n  7 #include<stdio.h>\r\n  8 \r\n  9 using namespace std;\r\n 10 \r\n 11 const long SECOND_IN_NS = 10000000001;  \/\/1second in nanoseconds\r\n 12 \r\n 13 class Timer  \/\/\u8ba1\u7b97\u65f6\u95f4\u5dee\u7684\u7c7b\r\n 14 {\r\n 15     private:\r\n 16     struct timespec m_start;\r\n 17     struct timespec m_end;\r\n 18     clockid_t m_clockId;\r\n 19     public:\r\n 20     Timer(){\r\n 21         init(true, true);\r\n 22     }\r\n 23 \r\n 24     Timer(bool realTime){\r\n 25         init(realTime, true);\r\n 26     }\r\n 27 \r\n 28     Timer(bool realTime, bool startImmediately){\r\n 29         init(realTime, startImmediately);\r\n 30     }\r\n 31 \r\n 32     void init(bool realTime, bool startImmediately){\r\n 33         if (realTime){\r\n 34             \/\/Real time\r\n 35             m_clockId = CLOCK_REALTIME; \/\/ is not a system call\r\n 36             \/\/m_clockId = CLOCK_MONOTONIC_RAW; \/\/is a system call\r\n 37         }\r\n 38         else{\r\n 39             \/\/Process CPU time across all CPU core (threads)\r\n 40             m_clockId = CLOCK_PROCESS_CPUTIME_ID;\r\n 41         }\r\n 42         if (startImmediately){\r\n 43             start();\r\n 44         }\r\n 45     }\r\n 46     \r\n 47     void start(){\r\n 48         clock_gettime(m_clockId, &m_start);\r\n 49         m_end = m_start;\r\n 50     }\r\n 51 \r\n 52     void stop(){\r\n 53         clock_gettime(m_clockId, &m_end);\r\n 54     }\r\n 55     \r\n 56     \/\/return - the passed time between start and last stop in nanoseconds\r\n 57     double getNseconds() const{\r\n 58         return (m_end.tv_sec - m_start.tv_sec) * SECOND_IN_NS + (m_end.tv_nsec - m_start.tv_nsec);    \r\n 59     }\r\n 60 \r\n 61     \/\/return - the passed time between start and last stop in seconds\r\n 62     double getSeconds() const{\r\n 63         return (m_end.tv_sec - m_start.tv_sec) + double(m_end.tv_nsec - m_start.tv_nsec) \/ SECOND_IN_NS; \r\n 64     }\r\n 65     \r\n 66     \/\/return - the passed seconds without need of stopping the execution\r\n 67     double getSecondsAndContinue() const{\r\n 68         struct timespec tempEnd;\r\n 69         clock_gettime(m_clockId, &tempEnd);\r\n 70         return (tempEnd.tv_sec - m_start.tv_sec) + double(tempEnd.tv_nsec - m_start.tv_nsec) \/ SECOND_IN_NS; \r\n 71     }\r\n 72 \r\n 73     time_t getS() const{\r\n 74         time_t ret = m_end.tv_sec - m_start.tv_sec;\r\n 75         if (m_end.tv_nsec < m_start.tv_nsec){\r\n 76            ret -= 1;\r\n 77         }\r\n 78 \r\n 79         return ret;\r\n 80     }\r\n 81     \r\n 82     time_t getNs() const{\r\n 83         if (m_end.tv_nsec >= m_start.tv_nsec){\r\n 84             return m_end.tv_nsec - m_start.tv_nsec;\r\n 85         }\r\n 86         return SECOND_IN_NS + m_end.tv_nsec - m_start.tv_nsec;\r\n 87     }\r\n 88     \r\n 89     friend std::ostream& operator <<(std::ostream& os, const Timer& timer); \r\n 90 };\r\n 91 \r\n 92 std::ostream& operator <<(std::ostream& os, const Timer& timer){\r\n 93     char nsBuf[10];  \/\/999, 999, 999\r\n 94     if (timer.m_end.tv_nsec >= timer.m_start.tv_nsec){\r\n 95         os << timer.m_end.tv_nsec - timer.m_start.tv_sec;\r\n 96         snprintf(nsBuf, sizeof(nsBuf), \"%09li\", timer.m_end.tv_nsec - timer.m_start.tv_nsec);\r\n 97     }\r\n 98     else{\r\n 99         os << timer.m_end.tv_nsec - timer.m_start.tv_sec - 1;\r\n100         snprintf(nsBuf, sizeof(nsBuf), \"%09li\", SECOND_IN_NS + timer.m_end.tv_nsec - timer.m_start.tv_nsec);\r\n101     }\r\n102     return os<<\".\"<<nsBuf;\r\n103 }    \r\n104 \r\n105 void set(int& n){       \/\/\u88abfor_each\u8c03\u7528\r\n106     static int value = 0;\r\n107     n = value++;\r\n108 }\r\n109 \r\n110 void print(int n){      \/\/\u88abfor_each\u8c03\u7528\r\n111     cout<<n<<endl;\r\n112 }\r\n113 \r\n114 int main(){\r\n115     \/*test short copy*\/\r\n116     vector<int> iVec(1000);\r\n117     for_each(iVec.begin(), iVec.end(), set);\r\n118     \/\/for_each(iVec.begin(), iVec.end(), print);\r\n119 \r\n120     int* pInt = new int[iVec.size()];\r\n121 \r\n122     Timer timer;\r\n123     copy(iVec.begin(), iVec.end(), pInt);\r\n124     timer.stop();\r\n125     cout<<\"the short copy cost(\"<<timer.getSeconds()<<\")'s\"<<endl;\r\n126 \r\n127     timer.start();\r\n128     int size = iVec.size();\r\n129     for (int i = 0; i < iVec.size(); i++)\r\n130     {\r\n131         pInt[i] = iVec[size - i - 1];\r\n132     }\r\n133     timer.stop();\r\n134     cout<<\"the short loop cost(\"<<timer.getSeconds()<<\")'s\"<<endl;\r\n135 \u3000\u3000 delete []pInt;\r\n136     cout<<\"---------------------------------------\"<<endl;\r\n137 \r\n138     \/*test long copy*\/\r\n139     vector<int> iVec2(1000000);\r\n140     for_each(iVec2.begin(), iVec2.end(), set);\r\n141     \/\/for_each(iVec.begin(), iVec.end(), print);\r\n142 \r\n143     int* pInt2 = new int[iVec2.size()];\r\n144 \r\n145     Timer timer2;\r\n146     copy(iVec2.begin(), iVec2.end(), pInt2);\r\n147     timer2.stop();\r\n148     cout<<\"the long copy cost(\"<<timer2.getSeconds()<<\")'s\"<<endl;\r\n149 \r\n150     timer2.start();\r\n151     int size2 = iVec2.size();\r\n152     for (int i = 0; i < iVec2.size(); i++)\r\n153     {\r\n154         pInt2[i] = iVec2[size2 - i - 1];\r\n155     }\r\n156     timer2.stop();\r\n157     cout<<\"the long loop cost(\"<<timer2.getSeconds()<<\")'s\"<<endl;\r\n158     delete []pInt2;\r\n159     return 0;\r\n160 }\r\n\u7f16\u8bd1\u547d\u4ee4: g++ -o test main.cpp -lrt<\/pre>\n
\"\u590d\u5236\u4ee3\u7801\"<\/a><\/span><\/div>\n<\/div>\n
\u6d4b\u8bd5\u7ed3\u679c,\u8ddf\u4f5c\u8005\u7684\u5927\u76f8\u5f84\u5ead,\u4e0d\u77e5\u662f\u548c\u539f\u56e0:<\/p>\n
\"\"<\/p>\n<\/div>\n
<\/div>\n
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\u5206\u7c7b:\u00a0c++<\/a><\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
\u539f\u6587\u5730\u5740 \u770b\u5230\u6709\u4eba\u5728\u7528std::copy<\/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":[119],"class_list":["post-4046","post","type-post","status-publish","format-standard","hentry","tag-03-"],"_links":{"self":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/4046","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=4046"}],"version-history":[{"count":0,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/posts\/4046\/revisions"}],"wp:attachment":[{"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/media?parent=4046"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/categories?post=4046"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/i007.cc\/wordpress\/wp-json\/wp\/v2\/tags?post=4046"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}