{"id":125,"date":"2019-06-29T11:26:00","date_gmt":"2019-06-29T03:26:00","guid":{"rendered":"http:\/\/www.mustenaka.cn\/?p=125"},"modified":"2019-07-02T07:59:53","modified_gmt":"2019-07-01T23:59:53","slug":"carememset","status":"publish","type":"post","link":"https:\/\/www.mustenaka.cn\/index.php\/2019\/06\/29\/carememset\/","title":{"rendered":"\u614e\u7528memset"},"content":{"rendered":"

\u614e\u7528memset<\/h1>\n

C\/C++\u7684\u5185\u5b58\u521d\u59cb\u5316\u51fd\u6570memset\u51fd\u6570\u4e00\u5b9a\u8981\u614e\u7528<\/p>\n

memset\u662f\u4e00\u4e2a\u6781\u5176\u65b9\u4fbf\u7684\u51fd\u6570\uff0c\u5176\u4e3b\u8981\u529f\u80fd\u662f\u521d\u59cb\u5316\u4e00\u6bb5\u5185\u5b58\u533a\u57df\uff0c\u6765\u81ea\u4e8e\u5934\u6587\u4ef6<string,h>\uff0c\u4f46\u662f\u8fd9\u4e2a\u51fd\u6570\u4e5f\u662f\u4e00\u4e2a\u76f8\u5bf9\u800c\u8a00\u5f88\u5bb9\u6613\u51fa\u9519\u7684\u51fd\u6570\uff0c\u8ba9\u6211\u4eec\u5148\u6765\u770b\u4e00\u4e0b\u4ed6\u7684\u89e3\u91ca\uff1a<\/p>\n

C++ Reference\u5bf9\u4e8ememset\u7684\u5b9a\u4e49\u4e3a\uff1a<\/p>\n

Fill block of memory
\nSets the first num bytes of the block of memory pointed by ptr to the specified value (interpreted as an unsigned char).<\/p>\n

<\/a>void\u00a0<\/span><\/em>memset ( void\u00a0<\/span>ptr, int value, size_t num );<\/em><\/strong><\/h6>\n

ptr\uff1a Pointer to the block of memory to fill.
\nvalue\uff1a Value to be set. The value is passed as an int, but the function fills the block of memory using the unsigned char conversion of this value.
\nnum\uff1aNumber of bytes to be set to the value.<\/em><\/p>\n

\u89e3\u91ca\u4e00\u4e0b\u5176\u4e2d\u7684\u4e09\u4e2a\u53c2\u6570\uff1a<\/h2>\n

Ptr\u8868\u793a\u4e00\u4e2a\u6307\u9488\uff0c\u5176\u6307\u5411\u4e00\u6bb5\u5185\u5b58
\nValue\u8868\u793a\u586b\u5145\u8fd9\u4e2a\u533a\u57df\u5185\u5b58\u7684\u503c
\nNum\u8868\u793a\u8fd9\u6bb5\u5185\u5b58\u533a\u95f4<\/p>\n

\u8fd9\u91cc\u53ef\u4ee5\u6ce8\u610f\u4e00\u4e0b\uff0c\u6211\u4eec\u901a\u5e38\u4f7f\u7528sizeof\u8fdb\u884cnum\u6bb5\u7684\u8868\u793a\uff0csizeof\u53ef\u4ee5\u5feb\u901f\u7684\u83b7\u53d6\u5230\u6240\u9700\u7a7a\u95f4\u7684\u5b57\u8282\u5927\u5c0f\uff0c\u8fd9\u901a\u5e38\u662f\u4e0e\u7c7b\u578b\u6240\u51b3\u5b9a\u7684\u3002
\n\u6bd4\u5982\u8bf4\u6211\u4eec\u53ef\u4ee5\u7ed9\u4e00\u4e2a\u6570\u7ec4\u521d\u59cb\u5316\u4e3a0\uff0c\u6d4b\u8bd5\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n

#include<iostream>\r\n#include<cstring>\r\nusing namespace std;\r\nconst int maxn=20;\r\nint a[maxn];\r\nint main(){\r\ncout<<\"memset \u4f7f\u7528\u524d\uff1a\"<<endl;\r\nfor(int i=0;i<maxn;i++){\r\ncout<<a[i]<<' ';\r\n}\r\ncout<<endl<<\"memset \u4f7f\u7528\u540e\uff1a\"<<endl;\r\nmemset(a,0,sizeof(a));\r\nfor(int i=0;i<maxn;i++){\r\ncout<<a[i]<<' ';\r\n}\r\ncout<<endl;\r\nreturn 0;\r\n}<\/code><\/pre>\n
<\/span><\/code><\/span><\/code>\u7ed3\u679c\u4e3a\uff1a
\nmemset \u4f7f\u7528\u524d\uff1a
\n0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
\nmemset \u4f7f\u7528\u540e\uff1a
\n0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0<\/p>\n
\u8fd9\u6837\u4e4d\u4e00\u770b\u6ca1\u4ec0\u4e48\u95ee\u9898\uff0c\u800c\u4e14\u6211\u4eec\u7684\u6570\u7ec4\u5728\u521b\u5efa\u7684\u540c\u65f6\u81ea\u5df1\u5c31\u5df2\u7ecf\u662f\u4e00\u4e2a\u8d4b\u503c\u4e3a0\u7684\u60c5\u51b5\u4e0b\u4e86\uff0c\u6240\u4ee5\u8fd9\u6837\u7684\u64cd\u4f5c\u6ca1\u6709\u4efb\u4f55\u95ee\u9898\uff0c\u6211\u4eec\u518d\u62ff\u5b57\u7b26\u6570\u7ec4\u8fdb\u884c\u4e00\u4e0b\u6d4b\u8bd5\uff0c\u4fee\u6539\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
#include<iostream>\r\n#include<cstring>\r\nusing namespace std;\r\nconst int maxn=20;\r\nchar a[maxn];\r\nint main(){\r\ncout<<\"memset \u4f7f\u7528\u524d\uff1a\"<<endl;\r\nfor(int i=0;i<maxn;i++){\r\ncout<<a[i]<<' ';\r\n}\r\ncout<<endl<<\"memset \u4f7f\u7528\u540e\uff1a\"<<endl;\r\nmemset(a,'A',sizeof(a));\r\nfor(int i=0;i<maxn;i++){\r\ncout<<a[i]<<' ';\r\n}\r\ncout<<endl;\r\nreturn 0;\r\n}<\/code><\/pre>\n
\u7ed3\u679c\u4e3a\uff1a
\nmemset \u4f7f\u7528\u524d\uff1a<\/p>\n
memset \u4f7f\u7528\u540e\uff1a
\nA A A A A A A A A A A A A A A A A A A A<\/p>\n
\u56e0\u4e3a\u6211\u4eec\u7684\u5b57\u7b26\u6570\u7ec4\u5728\u7a7a\u7684\u60c5\u51b5\u4e0b\u5bf9\u4e8eASCII\u7801\u8868\u683c\u7684\u7a7a\uff0c\u56e0\u6b64\u76f4\u63a5\u8fdb\u884c\u8f93\u51fa\u662f\u6ca1\u6709\u4efb\u4f55\u4e1c\u897f\u7684\uff0c\u4f46\u662f\u6211\u4eec\u5728\u4f7f\u7528memset\u51fd\u6570\u8fdb\u884c\u96c6\u4f53\u521d\u59cb\u5316\u4e4b\u540e\u4ed6\u5c31\u53d8\u5f97\u6709\u4e86\u503c\uff0c\u5982\u672c\u6837\u4f8b\u4ed6\u4f1a\u53d8\u6210\u5168\u90e8\u662f\u2019A\u2019\u7684\u5185\u5bb9\u3002<\/p>\n
\u63a5\u4e0b\u6765\u5c31\u662f\u95ee\u9898\u6240\u5728\u4e86
\n\u5982\u679c\u6211\u4eec\u60f3\u8981\u5c06\u5176\u5168\u90e8\u521d\u59cb\u5316\u4e00\u4e2a\u81ea\u5b9a\u4e49\u7684\u503c\u5462\uff1f\u6bd4\u5982\u8bf4\u5168\u90e8\u521d\u59cb\u5316\u4e3a1\uff0c\u53c8\u4f1a\u600e\u4e48\u6837\u5462\uff1f
\n\u6211\u4eec\u4fee\u6539\u6d4b\u8bd5\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
#include<iostream>\r\n#include<cstring>\r\nusing namespace std;\r\nconst int maxn=20;\r\nint a[maxn];\r\nint main(){\r\ncout<<\"memset \u4f7f\u7528\u524d\uff1a\"<<endl;\r\nfor(int i=0;i<maxn;i++){\r\ncout<<a[i]<<' ';\r\n}\r\ncout<<endl<<\"memset \u4f7f\u7528\u540e\uff1a\"<<endl;\r\nmemset(a,1,sizeof(a));\r\nfor(int i=0;i<maxn;i++){\r\ncout<<a[i]<<' ';\r\n}\r\ncout<<endl;\r\nreturn 0;\r\n}<\/code><\/pre>\n
\u5176\u7ed3\u679c\u4e3a\uff1a
\nmemset \u4f7f\u7528\u524d\uff1a
\n0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
\nmemset \u4f7f\u7528\u540e\uff1a
\n16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009 16843009<\/p>\n
\u8fd9\u4e0e\u6211\u4eec\u6240\u6c42\u7684\u7ed3\u679c\u5927\u76f8\u5f84\u5ead\uff0c\u6211\u4eec\u6240\u9700\u8981\u8d4b\u503c\u76841\u53bb\u54ea\u4e86\uff1f\u4e3a\u4ec0\u4e48\u662f16843009\u8fd9\u4e2a\u5b8c\u5168\u4e0d\u76f8\u5e72\u7684\u6570\u5b57\u5728\u91cc\u9762\uff0c\u96be\u9053\u6211\u4eec\u7684\u4ee3\u7801\u51fa\u9519\u4e86\u4e48\uff1f\u4e3a\u4e86\u6d4b\u8bd5\uff0c\u6211\u4eec\u53c8\u5c06\u5176\u5185\u5bb9\u8d4b\u503c\u4e3a\u4e862\uff0c\u7ed3\u679c\u6240\u6709\u7684\u6570\u636e\u53d8\u6210\u4e8633686018\u8fd9\u4e2a\u503c\uff0c\u540c\u6837\u4e0e\u6211\u4eec\u6240\u9700\u6c42\u7684\u7ed3\u679c\u4e0d\u76f8\u540c\u3002
\n\u8fd9\u662f\u4e3a\u4ec0\u4e48\u5462<\/p>\n
\u5176\u539f\u56e0\u5c31\u662f\u51fa\u5728\u6211\u4eecmemset\u7684\u5e95\u5c42\u8bbe\u8ba1\u4e0a\uff0cmemset\u662f\u91c7\u7528\u6bcf\u4e00\u4e2a\u5b57\u8282\u6bcf\u4e00\u4e2a\u5b57\u8282\u8fdb\u884c\u8d4b\u503c\u7684\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u6211\u4eec\u6240\u7ed9\u51fa\u76841\uff0c\u5176\u56e0\u4e3aint\u7c7b\u578b\u5360\u7528\u56db\u4e2a\u5b57\u8282\u7684\u539f\u56e0\u88ab\u6309\u7167\u5185\u5b58\u5206\u4e3a\u4e86\u56db\u4e2a\u90e8\u5206\uff0c\u6bcf\u4e00\u4e2a\u90e8\u5206\u5b58\u5728\u4e00\u4e2a1\uff0c\u56e0\u6b64\u7ecf\u8fc7memset\u51fd\u6570\u521d\u59cb\u5316\u4e4b\u540e\u7684\u6570\u7ec4\u7684\u5185\u5bb9\u5e94\u8be5\u6210\u4e86\u8fd9\u4e2a\u6837\u5b50\uff08\u4f7f\u7528\u4e8c\u8fdb\u5236\u8fdb\u884c\u8868\u793a\uff09<\/p>\n
0000 0001 0000 0001 0000 0001 0000 0001 \u51714\u4e2a\u5b57\u8282\uff0c\u6bcf\u4e00\u4e2a\u5b57\u8282\u5360\u75288\u4e2a\u4e8c\u8fdb\u5236\u4f4d
\n\u6211\u4eec\u518d\u6765\u8ba1\u7b97\u4e00\u4e0b\uff0c
\n\u4e3a\u4e86\u65b9\u4fbf\u7406\u89e3\uff0c\u8fd9\u91cc\u4e0d\u5199\u76f4\u63a5\u7684\u8fd0\u7b97\u51fd\u6570\uff0c\u800c\u662f\u4f7f\u7528C++\u7684bitset\u51fd\u6570\u8fdb\u884c\u6d4b\u8bd5\uff0c\u6211\u4eec\u76f4\u63a5\u628a\u6570\u636e\u653e\u5165bitset\u51fd\u6570\u4e2d\uff0c\u770b\u4e00\u4e0b\u4ed6\u8f6c\u6362\u51fa\u6765\u7684\u4e8c\u8fdb\u5236\u662f\u5426\u4e0e\u6211\u4eec\u4e4b\u524d\u7684\u9884\u671f\u76f8\u540c\u5373\u53ef\u3002<\/p>\n
#include<bits\/stdc++.h>\r\nusing namespace std;\r\nint main(){\r\nbitset<32> s(16843009);\r\ncout<<s<<endl;\r\nreturn 0;\r\n}<\/code><\/pre>\n
\u5176\u7ed3\u679c\u4e3a\uff1a
\n00000001 00000001 00000001 00000001
\n\uff08\u4e3a\u4e86\u65b9\u4fbf\u800c\u76f4\u89c2\u7684\u8868\u793a\u6211\u7a0d\u5fae\u7528\u4e86\u4e00\u4e0b\u7a7a\u683c\u505a\u5904\u7406\uff0c8\u4e2a\u4e8c\u8fdb\u5236\u4e00\u7ec4\uff09<\/p>\n
\u5b8c\u5168\u4e00\u81f4\uff0c\u56e0\u6b64\u6211\u4eec\u6839\u636e\u8fd9\u4e2a\u7ed3\u8bba\uff0c\u5f97\u51fa\u4e86\u4e00\u4e2a\u7ecf\u9a8c\uff1a<\/h4>\n
    \n
  1. \u5bf9\u4e8e\u6574\u5f62\u7b49\u7cbe\u5ea6\u57282\u5b57\u8282\u4ee5\u4e0a\u7684\u6570\u636e\u7c7b\u578b\uff0c\u9664\u4e86\u8d4b\u503c\u4e3a0 (\u5341\u516d\u7ea7\u8fdb\u52360x00)\u4e0e\u8d4b\u503c\u4e3a-1 (\u5341\u516d\u7ea7\u8fdb\u52360xff)\u4e4b\u5916\u7684\u6570\u636e\uff0c\u4e0d\u65b9\u4fbf\u8fdb\u884c\u76f4\u63a5\u7684\u521d\u59cb\u5316\u7684\u7ed3\u8bba\u3002<\/li>\n
  2. \u5bf9\u4e8e\u5b57\u7b26\u6570\u7ec4\u8fd9\u6837\u7684\u5355\u5b57\u8282\u6570\u636e\u7c7b\u578b\uff0c\u53ef\u4ee5\u65b9\u4fbf\u7684\u8fdb\u884c\u521d\u59cb\u5316<\/li>\n
  3. \u6b64\u5916\uff0cmemset\u76f8\u5f53\u4e8e\u4e00\u6b21\u4ece\u5934\u5230\u5c3e\u7684\u904d\u5386\uff0c\u5176\u672c\u8eab\u7684\u65f6\u95f4\u590d\u6742\u5ea6\u662fO(N)\u7ebf\u6027\u7ea7\u522b\u7684\uff0c\u4e0efor()\u5faa\u73af\u904d\u5386\u6574\u4e2a\u6570\u7ec4\u5e76\u4e14\u4f9d\u6b21\u8d4b\u503c\u5e76\u6ca1\u6709\u5176\u4ed6\u7684\u533a\u522b\uff0c\u5982\u679c\u5728\u6781\u5176\u82db\u523b\u7684\u65f6\u95f4\u590d\u6742\u5ea6\u6761\u4ef6\u4e0b\u8fd9\u4e2a\u51fd\u6570\u9700\u8981\u614e\u7528\u3002<\/li>\n<\/ol>\n
    \u603b\u4e4bmemset\u5fc5\u987b\u8981\u614e\u7528\uff0c\u81f3\u4e8e\u6211\u4e3a\u4ec0\u4e48\u53d1\u8fd9\u4e2a\u6587\u7ae0\uff0c\u8bf4\u591a\u4e86\u90fd\u662f\u6cea\u554a\uff0c\u8bf6\uff08\u80a5\u5b85\u5927\u54ed\uff09<\/p>\n","protected":false},"excerpt":{"rendered":"
    \u614e\u7528memset C\/C++\u7684\u5185\u5b58\u521d\u59cb\u5316\u51fd\u6570memset\u51fd\u6570\u4e00\u5b9a\u8981\u614e\u7528 memset\u662f\u4e00\u4e2a\u6781\u5176\u65b9\u4fbf\u7684 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[33],"class_list":["post-125","post","type-post","status-publish","format-standard","hentry","category-cpp","tag-c"],"views":3209,"_links":{"self":[{"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/posts\/125","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/comments?post=125"}],"version-history":[{"count":1,"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/posts\/125\/revisions"}],"predecessor-version":[{"id":126,"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/posts\/125\/revisions\/126"}],"wp:attachment":[{"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/media?parent=125"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/categories?post=125"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.mustenaka.cn\/index.php\/wp-json\/wp\/v2\/tags?post=125"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}