{"id":499,"date":"2024-12-25T00:41:29","date_gmt":"2024-12-24T16:41:29","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=499"},"modified":"2024-12-25T00:41:29","modified_gmt":"2024-12-24T16:41:29","slug":"%e6%b7%b1%e5%85%a5%e8%a7%a3%e6%9e%90%ef%bc%9a%e5%b8%b8%e9%87%8f%e5%8f%98%e9%87%8f%e4%b8%8e%e9%9d%9e%e5%b8%b8%e9%87%8f%e6%8c%87%e9%92%88%e4%b8%ba%e4%bd%95%e6%98%be%e7%a4%ba%e4%b8%8d%e5%90%8c%e5%86%85","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2024\/12\/25\/%e6%b7%b1%e5%85%a5%e8%a7%a3%e6%9e%90%ef%bc%9a%e5%b8%b8%e9%87%8f%e5%8f%98%e9%87%8f%e4%b8%8e%e9%9d%9e%e5%b8%b8%e9%87%8f%e6%8c%87%e9%92%88%e4%b8%ba%e4%bd%95%e6%98%be%e7%a4%ba%e4%b8%8d%e5%90%8c%e5%86%85\/","title":{"rendered":"\u6df1\u5165\u89e3\u6790\uff1a\u5e38\u91cf\u53d8\u91cf\u4e0e\u975e\u5e38\u91cf\u6307\u9488\u4e3a\u4f55\u663e\u793a\u4e0d\u540c\u5185\u5b58\u503c"},"content":{"rendered":"\n
\n

\u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5e38\u91cf\u53d8\u91cf\u548c\u975e\u5e38\u91cf\u6307\u9488\u53ef\u4ee5\u5728\u540c\u4e00\u5185\u5b58\u5730\u5740\u663e\u793a\u4e0d\u540c\u7684\u503c\uff0c\u8fd9\u662f\u7531\u4e8e \u672a\u5b9a\u4e49\u884c\u4e3a\uff08Undefined Behavior\uff09<\/strong> \u6216 \u7f16\u8bd1\u5668\u4f18\u5316<\/strong> \u5bfc\u81f4\u7684\u3002\u4ee5\u4e0b\u662f\u8be6\u7ec6\u539f\u56e0\u548c\u89e3\u91ca\uff1a<\/p>\n<\/blockquote>\n\n\n\n

\n\n\n\n

1. \u672a\u5b9a\u4e49\u884c\u4e3a\u5bfc\u81f4\u7684\u5dee\u5f02<\/strong><\/h3>\n\n\n\n

\u5f53\u7a0b\u5e8f\u5bf9\u5e38\u91cf\u53d8\u91cf\uff08const<\/code> \u4fee\u9970\u7684\u53d8\u91cf\uff09\u901a\u8fc7\u975e\u5e38\u91cf\u6307\u9488\u8fdb\u884c\u4fee\u6539\u65f6\uff0c\u5c31\u53ef\u80fd\u89e6\u53d1\u672a\u5b9a\u4e49\u884c\u4e3a\u3002\u8fd9\u79cd\u884c\u4e3a\u53ef\u80fd\u5bfc\u81f4\u7a0b\u5e8f\u5728\u67d0\u4e9b\u73af\u5883\u4e0b\u51fa\u73b0\u540c\u4e00\u5185\u5b58\u5730\u5740\u663e\u793a\u4e0d\u540c\u503c\u7684\u60c5\u51b5\u3002<\/p>\n\n\n\n

\u793a\u4f8b\uff1a<\/h4>\n\n\n\n
#include <iostream>\n\nint main() {\n    const int a = 42; \/\/ \u5e38\u91cf\u53d8\u91cf\n    int* p = (int*)&a; \/\/ \u975e\u5e38\u91cf\u6307\u9488\u6307\u5411\u5e38\u91cf\u53d8\u91cf\n    *p = 100; \/\/ \u4fee\u6539\u5185\u5b58\u5730\u5740\u7684\u503c\n\n    std::cout << \"a: \" << a << std::endl; \/\/ \u8f93\u51fa\u5e38\u91cf\u53d8\u91cf\n    std::cout << \"*p: \" << *p << std::endl; \/\/ \u8f93\u51fa\u6307\u9488\u6307\u5411\u7684\u503c\n    return 0;\n}<\/code><\/pre>\n\n\n\n
\u8f93\u51fa\u53ef\u80fd\u662f\uff1a<\/strong><\/p>\n\n\n\n
a: 42\n*p: 100<\/code><\/pre>\n\n\n\n
\u539f\u56e0\uff1a<\/strong><\/p>\n\n\n\n
    \n
  • a<\/code> \u88ab\u58f0\u660e\u4e3a const<\/code>\uff0c\u7f16\u8bd1\u5668\u53ef\u80fd\u4f1a\u5bf9 a<\/code> \u7684\u503c\u8fdb\u884c\u4f18\u5316\uff0c\u5c06 a<\/code> \u7684\u503c\u5185\u8054\uff08\u76f4\u63a5\u4f7f\u7528\u5e38\u91cf\u503c 42<\/code>\uff09\u3002<\/li>\n\n\n\n
  • \u975e\u5e38\u91cf\u6307\u9488\u4fee\u6539\u4e86 a<\/code> \u7684\u5185\u5b58\uff0c\u4f46\u7a0b\u5e8f\u4e2d\u8bbf\u95ee a<\/code> \u65f6\u4f7f\u7528\u7684\u662f\u7f16\u8bd1\u5668\u4f18\u5316\u540e\u7684\u5185\u8054\u503c\u3002<\/li>\n<\/ul>\n\n\n\n
    \n\n\n\n
    2. \u7f16\u8bd1\u5668\u4f18\u5316\u7684\u5f71\u54cd<\/strong><\/h3>\n\n\n\n
    const<\/code> \u53d8\u91cf\u5728\u7f16\u8bd1\u65f6\u901a\u5e38\u4f1a\u88ab\u89c6\u4e3a\u4e0d\u53ef\u66f4\u6539\uff0c\u56e0\u6b64\u7f16\u8bd1\u5668\u53ef\u80fd\u4f1a\u5c06\u5176\u503c\u4f18\u5316\u4e3a\u53ea\u8bfb<\/strong>\u3001\u5185\u8054\u5e38\u91cf<\/strong>\u6216\u5b58\u50a8\u5728\u53ea\u8bfb\u6bb5\u4e2d<\/strong>\u3002\u8fd9\u53ef\u80fd\u5bfc\u81f4\u4ee5\u4e0b\u60c5\u51b5\uff1a<\/p>\n\n\n\n
      \n
    • \u76f4\u63a5\u8bbf\u95ee const<\/code> \u53d8\u91cf\u65f6\uff0c\u8bfb\u53d6\u7684\u662f\u4f18\u5316\u540e\u7684\u5e38\u91cf\u503c\u3002<\/li>\n\n\n\n
    • \u4f7f\u7528\u975e\u5e38\u91cf\u6307\u9488\u4fee\u6539\u503c\u65f6\uff0c\u8bbf\u95ee\u7684\u662f\u5b9e\u9645\u5185\u5b58\u4e2d\u7684\u503c\u3002<\/li>\n<\/ul>\n\n\n\n
      \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
      #include <iostream>\n\nint main() {\n    const int x = 5;\n    int* ptr = (int*)&x;\n\n    *ptr = 10;\n\n    std::cout << \"x: \" << x << std::endl;   \/\/ \u53ef\u80fd\u8f93\u51fa 5\n    std::cout << \"*ptr: \" << *ptr << std::endl; \/\/ \u8f93\u51fa 10\n    return 0;\n}<\/code><\/pre>\n\n\n\n
      \u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff1a<\/p>\n\n\n\n
        \n
      • x<\/code> \u7684\u503c\u5728\u7f16\u8bd1\u5668\u4e2d\u88ab\u4f18\u5316\u4e3a\u5e38\u91cf 5<\/code>\u3002<\/li>\n\n\n\n
      • \u901a\u8fc7\u6307\u9488\u4fee\u6539\u4e86\u5185\u5b58\u4e2d\u7684\u503c\u4e3a 10<\/code>\u3002<\/li>\n\n\n\n
      • x<\/code> \u7684\u8f93\u51fa\u4f9d\u8d56\u4e8e\u7f16\u8bd1\u5668\u662f\u5426\u4f7f\u7528\u4e86\u4f18\u5316\u3002\u5982\u679c x<\/code> \u7684\u503c\u88ab\u5185\u8054\uff0c\u8f93\u51fa\u4ecd\u4e3a 5<\/code>\u3002<\/li>\n<\/ul>\n\n\n\n
        \n\n\n\n
        3. \u5185\u5b58\u6a21\u578b\u548c\u53ea\u8bfb\u6bb5\u7684\u5dee\u5f02<\/strong><\/h3>\n\n\n\n
        \u5982\u679c\u5e38\u91cf\u5b58\u50a8\u5728\u53ea\u8bfb\u6bb5\uff08\u5982 .rodata<\/code>\uff09\u4e2d\uff0c\u5f3a\u884c\u901a\u8fc7\u6307\u9488\u4fee\u6539\u53ef\u80fd\u5bfc\u81f4\u672a\u5b9a\u4e49\u884c\u4e3a\u3002<\/p>\n\n\n\n
        \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
        const int y = 20; \/\/ \u901a\u5e38\u5b58\u50a8\u5728\u53ea\u8bfb\u6bb5\u4e2d\nint* py = (int*)&y;\n*py = 30; \/\/ \u53ef\u80fd\u5bfc\u81f4\u7a0b\u5e8f\u5d29\u6e83\u6216\u672a\u5b9a\u4e49\u884c\u4e3a<\/code><\/pre>\n\n\n\n
        \u89e3\u91ca\uff1a<\/strong><\/p>\n\n\n\n
          \n
        • y<\/code> \u88ab\u7f16\u8bd1\u5668\u653e\u7f6e\u5230\u53ea\u8bfb\u6bb5\uff0c\u4efb\u4f55\u5c1d\u8bd5\u5199\u5165\u8be5\u6bb5\u90fd\u4f1a\u5bfc\u81f4\u9519\u8bef\u6216\u672a\u5b9a\u4e49\u884c\u4e3a\u3002<\/li>\n<\/ul>\n\n\n\n
          \n\n\n\n
          4. \u591a\u7ebf\u7a0b\u73af\u5883\u4e2d\u7684\u5dee\u5f02<\/strong><\/h3>\n\n\n\n
          \u5728\u591a\u7ebf\u7a0b\u73af\u5883\u4e2d\uff0c\u5982\u679c\u4e00\u4e2a\u7ebf\u7a0b\u901a\u8fc7\u975e\u5e38\u91cf\u6307\u9488\u4fee\u6539\u503c\uff0c\u800c\u53e6\u4e00\u4e2a\u7ebf\u7a0b\u8bfb\u53d6 const<\/code> \u53d8\u91cf\uff0c\u53ef\u80fd\u4f1a\u5bfc\u81f4\u4e24\u4e2a\u7ebf\u7a0b\u770b\u5230\u4e0d\u540c\u7684\u503c\u3002<\/p>\n\n\n\n
          \u793a\u4f8b\uff1a<\/h4>\n\n\n\n
          #include <iostream>\n#include <thread>\n\nconst int sharedVar = 50;\nvoid writer() {\n    int* p = (int*)&sharedVar;\n    *p = 100; \/\/ \u4fee\u6539\u503c\n}\n\nvoid reader() {\n    std::cout << \"sharedVar: \" << sharedVar << std::endl;\n}\n\nint main() {\n    std::thread t1(writer);\n    std::thread t2(reader);\n\n    t1.join();\n    t2.join();\n\n    return 0;\n}<\/code><\/pre>\n\n\n\n
          \u53ef\u80fd\u7684\u8f93\u51fa\uff1a<\/strong><\/p>\n\n\n\n
          sharedVar: 50<\/code><\/pre>\n\n\n\n
          \u539f\u56e0\uff1a<\/strong><\/p>\n\n\n\n
            \n
          • \u7f16\u8bd1\u5668\u53ef\u80fd\u5bf9 sharedVar<\/code> \u8fdb\u884c\u5185\u8054\u6216\u7f13\u5b58\u3002<\/li>\n\n\n\n
          • \u4fee\u6539\u901a\u8fc7\u6307\u9488\u5b8c\u6210\uff0c\u4f46\u8bfb\u53d6\u65f6\u4ecd\u4f7f\u7528\u7f13\u5b58\u7684\u503c\u3002<\/li>\n<\/ul>\n\n\n\n
            \n\n\n\n
            \u89e3\u51b3\u65b9\u6848\u548c\u5efa\u8bae<\/h3>\n\n\n\n
              \n
            1. \u907f\u514d\u672a\u5b9a\u4e49\u884c\u4e3a<\/strong>\uff1a\u4e0d\u8981\u901a\u8fc7\u975e\u5e38\u91cf\u6307\u9488\u4fee\u6539\u5e38\u91cf\u53d8\u91cf\uff0c\u8fd9\u4f1a\u5bfc\u81f4\u7a0b\u5e8f\u884c\u4e3a\u4e0d\u53ef\u9884\u6d4b\u3002<\/li>\n\n\n\n
            2. \u4f7f\u7528\u6b63\u786e\u7684\u5185\u5b58\u8bed\u4e49<\/strong>\uff1a<\/li>\n<\/ol>\n\n\n\n
                \n
              • \u5982\u679c\u9700\u8981\u4fee\u6539\u53d8\u91cf\uff0c\u79fb\u9664 const<\/code> \u4fee\u9970\u7b26\u3002<\/li>\n\n\n\n
              • \u5982\u679c\u53d8\u91cf\u662f\u5171\u4eab\u7684\uff0c\u4f7f\u7528 volatile<\/code> \u6216\u539f\u5b50\u64cd\u4f5c\u786e\u4fdd\u4e00\u81f4\u6027\u3002<\/li>\n<\/ul>\n\n\n\n
                  \n
                1. \u7406\u89e3\u7f16\u8bd1\u5668\u4f18\u5316<\/strong>\uff1a<\/li>\n<\/ol>\n\n\n\n
                    \n
                  • \u7f16\u8bd1\u5668\u53ef\u80fd\u4f1a\u5185\u8054\u6216\u7f13\u5b58\u5e38\u91cf\u503c\uff0c\u5bfc\u81f4\u4e0e\u5b9e\u9645\u5185\u5b58\u4e2d\u7684\u503c\u4e0d\u540c\u6b65\u3002<\/li>\n<\/ul>\n\n\n\n
                    \u8fd9\u79cd\u95ee\u9898\u901a\u5e38\u662f\u7f16\u7a0b\u5b9e\u8df5\u4e2d\u7684\u9519\u8bef\uff0c\u907f\u514d\u6ee5\u7528 const<\/code> \u548c\u7c7b\u578b\u5f3a\u5236\u8f6c\u6362\u662f\u5173\u952e\u3002\u66f4\u591a\u8be6\u7ec6\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"
                    \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\uff0c\u5e38\u91cf\u53d8\u91cf\u548c\u975e\u5e38\u91cf\u6307\u9488\u53ef\u4ee5\u5728\u540c\u4e00\u5185\u5b58\u5730\u5740\u663e\u793a\u4e0d\u540c\u7684\u503c\uff0c\u8fd9\u662f\u7531\u4e8e \u672a\u5b9a\u4e49\u884c\u4e3a\uff08Undefined B […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[59],"tags":[],"class_list":["post-499","post","type-post","status-publish","format-standard","hentry","category-c"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/499","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=499"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/499\/revisions"}],"predecessor-version":[{"id":500,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/499\/revisions\/500"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=499"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=499"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=499"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}