{"id":325091,"date":"2021-02-06T15:46:01","date_gmt":"2021-02-06T07:46:01","guid":{"rendered":"http:\/\/4563.org\/?p=325091"},"modified":"2021-02-06T15:46:01","modified_gmt":"2021-02-06T07:46:01","slug":"c%e4%b8%ad%e5%a4%9a%e7%ba%bf%e7%a8%8b%e6%93%8d%e4%bd%9c-string-%e5%bc%95%e5%8f%91%e7%9a%84-coredump%ef%bc%8c%e6%a0%88%e4%b8%ad%e6%af%94%e8%be%83%e5%a5%87%e6%80%aa%e7%9a%84%e4%b8%80%e7%82%b9","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=325091","title":{"rendered":"c++\u4e2d\u591a\u7ebf\u7a0b\u64cd\u4f5c string \u5f15\u53d1\u7684 coredump\uff0c\u6808\u4e2d\u6bd4\u8f83\u5947\u602a\u7684\u4e00\u70b9"},"content":{"rendered":"
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c++\u4e2d\u591a\u7ebf\u7a0b\u64cd\u4f5c string \u5f15\u53d1\u7684 coredump\uff0c\u6808\u4e2d\u6bd4\u8f83\u5947\u602a\u7684\u4e00\u70b9 <\/h1>\n

<\/p>\n

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\u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span> <\/i> 1<\/span> <\/div>\n
<\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n
<\/p>\n

\u6e90\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n

#include <iostream> #include <string> #include <vector> #include <thread>  struct A {     std::string name = \"blacksmith\";     int age = 100; };  struct B1 {     std::string local_name = \"jd-B1\";      void func1(A* a) {         while (true) {             a->name = local_name;             std::string key = local_name + \"**\";         }     } };  struct B2 {     std::string local_name = \"jd-B2\";      void func1(A* a) {         while (true) {             a->name = local_name;             std::string key = local_name + \"**\";         }     } };   int main() {     \/**      * \u63a2\u6d4b\u662f\u5426\u652f\u6301 COW      *\/     std::string* test = new std::string(\"blacksmith\");     std::string name = *test;     std::cout << \"test:\" << test->data() << \", name=\" << name.data() << std::endl;     if (test->data() == name.data()) {         std::cout << \"COW(Copy On Write) support!\" << std::endl;     } else {         std::cout << \"COW(Copy On Write) NOT support!\" << std::endl;     }     delete test;       \/**      * \u591a\u7ebf\u7a0b\u64cd\u4f5c      *\/     std::vector<std::thread> th_vec;     int thread_count = 4;     A a;     B1 b1;     B2 b2;     for (int i = 0; i < thread_count; i++) {         th_vec.emplace_back([&](){             b1.func1(&a);         });         th_vec.emplace_back([&](){             b2.func1(&a);         });     }      for (auto& item : th_vec) {         item.join();     }      std::cout << \"=========END==========\" << std::endl;      return 0; } <\/code><\/pre>\n
\u7f16\u8bd1\uff1a<\/p>\n
g++ --std=c++11 string-test.cc -g -lpthread <\/code><\/pre>\n
\u67e5\u770b coredump \u6808\uff1a<\/p>\n
(gdb) bt #0  0x00007f5613350e20 in __memcpy_ssse3 () from \/usr\/lib64\/libc.so.6 #1  0x00007f5613ba8650 in std::string::_Rep::_M_clone(std::allocator<char> const&, unsigned long) () from \/usr\/lib64\/libstdc++.so.6 #2  0x00007f5613ba86d4 in std::string::reserve(unsigned long) () from \/usr\/lib64\/libstdc++.so.6 #3  0x00007f5613ba893f in std::string::append(char const*, unsigned long) () from \/usr\/lib64\/libstdc++.so.6 #4  0x0000000000402808 in std::operator+<char, std::char_traits<char>, std::allocator<char> > (     __lhs=\"jd-B2\", '\u000000' <repeats 11 times>, \"!\u000000\u000000\u000000\u000000\u000000\u000000[email protected]@\u000000\u000000\u000000\u000000\u000000(I213\u000071375177\u000000\u000000\u000060I213\u000071375177\u000000\u000000Q\u000002\u000000\u000000\u000000\u000000\u000000\u000000\"\", '\u000000' <repeats 15 times>, \"\u000001\", '\u000000' <repeats 15 times>, \"377377377377377377377377\u000000\u000000\u000000\u000000\u000000\u000000\u000000\u000000377377377377377377377377\", '\u000000' <repeats 88 times>..., __rhs=0x40386a \"**\")     at \/opt\/rh\/devtoolset-7\/root\/usr\/include\/c++\/7\/bits\/basic_string.h:5917 #5  0x000000000040263f in B2::func1 (this=0x7ffd398b4920, a=0x7ffd398b4930) at string-test.cc:28 #6  0x0000000000401108 in <lambda()>::operator()(void) const (__closure=0x19a5368) at string-test.cc:62 #7  0x0000000000401fde in std::__invoke_impl<void, main()::<lambda()> >(std::__invoke_other, <lambda()> &&) (__f=...) at \/opt\/rh\/devtoolset-7\/root\/usr\/include\/c++\/7\/bits\/invoke.h:60 #8  0x0000000000401cb0 in std::__invoke<main()::<lambda()> >(<lambda()> &&) (__fn=...) at \/opt\/rh\/devtoolset-7\/root\/usr\/include\/c++\/7\/bits\/invoke.h:95 #9  0x0000000000402392 in std::thread::_Invoker<std::tuple<main()::<lambda()> > >::_M_invoke<0>(std::_Index_tuple<0>) (this=0x19a5368) at \/opt\/rh\/devtoolset-7\/root\/usr\/include\/c++\/7\/thread:234 #10 0x000000000040233f in std::thread::_Invoker<std::tuple<main()::<lambda()> > >::operator()(void) (this=0x19a5368) at \/opt\/rh\/devtoolset-7\/root\/usr\/include\/c++\/7\/thread:243 #11 0x00000000004022fe in std::thread::_State_impl<std::thread::_Invoker<std::tuple<main()::<lambda()> > > >::_M_run(void) (this=0x19a5360) at \/opt\/rh\/devtoolset-7\/root\/usr\/include\/c++\/7\/thread:186 #12 0x000000000040343f in execute_native_thread_routine () #13 0x00007f5613df8dd5 in start_thread () from \/usr\/lib64\/libpthread.so.0 #14 0x00007f5613302ead in clone () from \/usr\/lib64\/libc.so.6 <\/code><\/pre>\n
\u6bd4\u8f83\u7591\u60d1\u7684\u4e00\u70b9\u662f\uff0c\u591a\u7ebf\u7a0b\u5199 string\uff0c\u4e3a\u4ec0\u4e48\u4e0d\u662f\u5728\u5199\u5165\u90a3\u4e00\u884c core\uff0c\u800c\u662f\u5728\u540e\u9762\u62fc\u63a5\u6210\u5458\u53d8\u91cf\uff1f<\/p>\n
a->name = local_name; \/\/ \u6211\u7406\u89e3\u5e94\u8be5\u662f\u8fd9\u4e00\u884c\u62a5 core<\/p>\n
std::string key = local_name + “**”; \/\/ \u5b9e\u9645\u5728\u64cd\u4f5c local_name \u7684\u65f6\u5019 core\uff0c\u5e76\u4e14\u770b\u6808\uff0clocal_name \u5185\u5b58\u4e71\u4e86<\/p>\n
\u8f9b\u82e6\u5404\u4f4d\u5927\u4f6c\uff0c\u6709\u65f6\u95f4\u7684\u5e2e\u5fd9\u770b\u770b\uff0c\u5f88\u662f\u7591\u60d1\u3002 \u8c22\u8c22\u3002<\/p>\n<\/p><\/div>\n
 \u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (23<\/span>)        <\/div>\n
 <\/div>\n<\/p><\/div>\n<\/p><\/div>\n
    \n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : yianing <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 a->name \u5199\u5165\u7684\u65f6\u5019\u53ea\u662f\u62f7\u8d1d\u4e86 header \u90e8\u5206\uff0c\u867d\u7136\u4e5f\u662f\u591a\u5199\u4f46\u662f\u5199\u5165\u90fd\u662f\u540c\u4e00\u4efd\u6570\u636e\uff0c\u6ca1\u62a5\u9519\u53ea\u80fd\u8bf4\u8fd0\u6c14\u597d\u5427\uff0c\u4e0b\u9762 appen \u7684\u5730\u65b9\u5c31\u662f\u591a\u4e2a\u7ebf\u7a0b\u64cd\u4f5c\u4e00\u4efd\u6307\u9488\u6570\u636e\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : yianing <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @yianing golang \u91cc\u9762\u7684 string \u662f\u4e0d\u53ef\u53d8\u7684\uff0c\u6211\u7528 int \u6d4b\u8bd5\u4e00\u4e0b
    “`go
    package main<\/p>\n
    import “time”<\/p>\n
    type A struct {
     age int
    }<\/p>\n
    type B struct {
     age int
    }<\/p>\n
    func (b *B) Op(a *A) {
     for {
     a.age++
     b.age++
     }
    }<\/p>\n
    func main() {
     b := &B{}
     a := &A{}
     for i := 0; i < 3; i++ {
     go b.Op(a)
     }
     time.Sleep(100 * time.Millisecond)
    }
    “`
    go run -race \u7684\u65f6\u5019\u4e24\u4e2a++\u90fd\u662f\u4f1a\u62a5\u9519\u7684                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : secondwtq <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u591a\u7ebf\u7a0b\u5199\u5165\uff0c\u7ed3\u679c\u5c31\u662f\u5199\u5165\u7684\u6570\u636e\u4e0d\u53ef\u9760\uff0c\u4e0d\u662f\u76f4\u63a5\u7ed9\u4f60\u62a5\u9519\u3002
    \u53ea\u6709\u4f60\u518d\u4f7f\u7528\u5199\u5165\u7684\u6570\u636e\u65f6\u624d\u4f1a\u628a\u95ee\u9898\u66b4\u9732\u51fa\u6765\uff0c\u800c\u5728\u5b9e\u9645\u7a0b\u5e8f\u4e2d\u5f88\u96be\u77e5\u9053\u662f\u8c01\u4ec0\u4e48\u65f6\u5019\u5199\u5165\u7684\u6570\u636e\uff0c\u8fd9\u662f\u5e76\u53d1\u9519\u8bef\u96be\u8c03\u8bd5\u7684\u539f\u56e0\u4e4b\u4e00\uff0c\u62a5\u9519\u7684\u70b9\u4e0d\u4e00\u5b9a\u662f data race \u53d1\u751f\u7684\u70b9\u3002<\/p>\n
    \u6709\u65f6\u5019\u4e5f\u4f1a\u6545\u610f\u8fd9\u4e48\u505a\uff0c\u6027\u80fd\u4f1a\u597d\u4e00\u4e9b\uff0c                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : hxndg <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u9996\u5148\uff0c\u4f60\u8fd9\u4e2a\u5e94\u8be5\u4e0d\u4f1a\u53ea\u51fa\u73b0\u4e00\u79cd core \u7684\u7ed3\u679c
    27 \u884c\u5e94\u8be5\u4e5f\u53ef\u80fd\u51fa\u73b0 core\uff0c\u4f46 core \u7684\u539f\u56e0\u5e94\u8be5\u662f\u591a\u4e2a\u7ebf\u7a0b free \u540c\u4e00\u4e2a\u5730\u65b9\u5bfc\u81f4\u7684\u3002<\/p>\n
    \u53e6\u5916 28 \u884c\u51fa\u73b0 core \u7684\u539f\u56e0\u770b\u6d41\u7a0b\u50cf\u662f\u62f7\u8d1d\u7684\u65f6\u5019\u751f\u6210\u7684\u4e34\u65f6\u53d8\u91cf\u90fd\u662f\u5728 local_name \u4e0a\uff0c\u7136\u540e\u4e0d\u540c\u7ebf\u7a0b\u64cd\u4f5c\u5bfc\u81f4\u62f7\u8d1d\u7684\u957f\u5ea6\u65e0\u6548\u5bfc\u81f4\u7684\u3002<\/p>\n
    \u5f53\u7136\u4ee5\u4e0a\u7ed3\u8bba\u9700\u8981\u4e8b\u5b9e+\u89c2\u5bdf\u5bc4\u5b58\u5668\u4f20\u53c2\u786e\u5b9a\uff0c\u6211\u5fd8\u4e86 X86_64 \u4f4d\u4e0b\u5bc4\u5b58\u5668\u7684\u503c\u4ee3\u8868\u7684\u542b\u4e49\u4e86\uff0c\u4e0d\u505a\u4efb\u4f55\u6b63\u786e\u6027\u4fdd\u8bc1\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : matrixji <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u4e3b\u4f60\u786e\u5b9a\u8fd9\u4e2a\u95ee\u9898\u4e0d\u662f\u6df7\u7528\u4e86 devtoolset-7 \u548c\u7cfb\u7edf\u7684 libstdc++\u5bfc\u81f4\u7684\u3002
    \u4ece C++11 \u672c\u7701\u6765\u8bb2 a->name = local_name; \u8d70\u7684\u662f operator= \u7531\u4e8e local_name \u7684\u957f\u5ea6 \u5927\u4e8e A::name \u5b9e\u9645\u4e0a\u8fd9\u91cc\u90fd\u4e0d\u4f1a\u53d1\u751f\u5185\u5b58\u7684\u91ca\u653e\u548c\u7533\u8bf7\uff0c\u53ea\u4f1a\u6709 Copy \u64cd\u4f5c\u3002\u6240\u4ee5\u8fd9\u91cc\u5e94\u8be5\u4e0d\u4f1a\u6709\u5185\u5b58\u9519\u8bef\u624d\u5bf9\u3002
    \u81f3\u4e8e std::string key = local_name + “**”; \u5c31\u5e94\u8be5\u66f4\u52a0\u6ca1\u6709\u95ee\u9898\u4e86\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : imjamespond <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 string \u672c\u8d28\u4e0a\u597d\u50cf\u662f\u4e2a vector                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
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     \u8cc7\u6df1\u5927\u4f6c : Wirbelwind <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5347\u7ea7\u4e00\u4e0b\u7f16\u8bd1\u5668<\/p>\n
    msvc \u6ca1\u80fd\u590d\u73b0\u51fa\u6765<\/p>\n
    \u6bcf\u4e2a\u7ebf\u7a0b\u8bfb\u53d6\u7684\u90fd\u662f\u7ebf\u7a0b\u5185 local_name\uff0c\u800c\u4e14 local_name \u6ca1\u6709\u88ab\u5199\u5165\u8fc7\uff0c
    \u5e94\u8be5\u4e0d\u4f1a\u6709\u8fd9\u79cd\u60c5\u51b5                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @yianing \u8c22\u8c22\u8be6\u7ec6\u7684\u8bb2\u89e3\u3002\u5728 append \u7684\u5730\u65b9\uff0c\u90fd\u662f\u53ea\u8bfb\u7684\u6210\u5458\u53d8\u91cf local_name\uff0c\u5e76\u6ca1\u6709\u53bb\u5199\u3002\u4f46\u662f\u6808\u4e2d\u663e\u793a\u7684\u8fd9\u4e2a\u53d8\u91cf\u5185\u5b58\u4e71\u4e86\uff0c\u6bd4\u8f83\u8ba9\u4eba\u8be7\u5f02\u3002\u6309\u8bf4\u5e94\u8be5\u662f a->name \u7684\u5185\u5b58\u6709\u95ee\u9898\u624d\u5bf9\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @secondwtq 
    \u662f\u7684\uff0c\u6211\u5f00\u59cb\u4e5f\u8ba4\u4e3a\u5199\u5165\u4f1a\u5bfc\u81f4\u6570\u636e\u4e0d\u51c6\u786e\u3002\u4f46\u662f local_name \u53d8\u91cf\u662f\u4e00\u4e2a\u6210\u5458\u53d8\u91cf\uff0c\u5e76\u6ca1\u6709\u53bb\u4fee\u6539\u5b83\u3002\u5f00\u59cb\u6000\u7591\u662f cow \u7684\u4e00\u4e9b\u673a\u5236\u5bfc\u81f4\u7684\uff0c\u4f46\u662f\u6211\u627e\u4e0d\u5230\u4efb\u4f55\u7684\u8bc1\u636e\u3002\u7ebf\u4e0a\u53d1\u751f\u4e86\u7c7b\u4f3c\u7684 core\uff0c\u6808\u7684\u5730\u65b9\u548c\u5b9e\u9645\u7684\u64cd\u4f5c\u6709\u95ee\u9898\u7684\u5730\u65b9\u4e0d\u4e00\u81f4\uff0c\u5bfc\u81f4\u6392\u67e5\u7684\u65f6\u5019\u9700\u8981\u901a\u89c8\u4e00\u4e0b\u4ee3\u7801\uff0c\u6211\u5728\u60f3\u6709\u6ca1\u6709\u4ec0\u4e48\u65b9\u6cd5\u53ef\u4ee5\u76f4\u63a5\u5b9a\u4f4d\u5230\u5199\u9519\u8bef\u7684\u5730\u65b9\uff1f                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @hxndg \u975e\u5e38\u611f\u8c22\u3002\u786e\u5b9e\u4f1a\u6709\u4e24\u79cd coredump \u53d1\u751f\u3002
    \u7b2c\u4e00\u79cd 27 \u884c\u7684\u90a3\u4e2a\uff0c\u6bd4\u8f83\u597d\u7406\u89e3\u3002
    \u53d1\u751f\u5728 28 \u884c\u7684\u8fd9\u4e2a core \u5176\u5b9e\u4e0d\u592a\u7b26\u5408\u9884\u671f\uff0c\u5982\u679c\u62f7\u8d1d\u7684\u4e34\u65f6\u53d8\u91cf\u4e0d\u662f\u5b58\u50a8\u5728\u5de6\u8fb9\u7684\u503c\uff0c\u800c\u662f\u53f3\u8fb9\u7684\u503c\uff0c\u90a3\u4e48\u53ef\u4ee5\u8bf4\u7684\u901a\u3002\u4f46\u662f\u6211\u786e\u5b9e\u6ca1\u6709\u627e\u5230\u7c7b\u4f3c\u7684\u8bc1\u636e\uff0c\u8bc1\u660e\u8fd9\u4e00\u70b9\u3002
    \u8c22\u8c22\u4e86\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @matrixji \u5e94\u8be5\u4e0d\u662f\u7684\uff0c\u6211\u5f00\u59cb\u7684\u7248\u672c\u6ca1\u6709\u4f7f\u7528 devtooset-7\uff0c\u4e5f\u6709\u95ee\u9898\uff0c\u540e\u9762\u60f3\u5347\u7ea7 gcc \u7248\u672c\uff0c\u53d1\u73b0\u4e5f\u662f\u7c7b\u4f3c\u7684\u95ee\u9898\u3002
    coredump \u7684\u5185\u5bb9\u786e\u5b9e\u5982\u6211\u5e16\u5b50\u91cc\u7684\u3002\u5f88\u662f\u5947\u602a\u4e3a\u5565 std::string key = local_name + “**”;\u8fd9\u4e00\u884c\u4f1a\u6709\u95ee\u9898\u3002
    \u8c22\u8c22\u56de\u590d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @imjamespond \u6000\u7591\u662f cow \u505a\u4e86\u4ec0\u4e48\u52a8\u4f5c\uff0c\u53ef\u662f\u6211\u6ca1\u6709\u8bc1\u636e:)
    \u8c22\u8c22\u56de\u590d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
    \n
     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Wirbelwind 
    \u53ef\u80fd\u8ddf\u7f16\u8bd1\u5668\u6709\u5173\u5427\u3002\u6211\u7528 4.8.5 \u548c 7 \u7684\u7248\u672c\u90fd\u8bd5\u4e86\u4e0b\uff0c\u90fd\u662f\u6709\u95ee\u9898\u7684\u3002\u76ee\u524d\u6211\u8fd9\u6ca1\u6709 msvc \u7684\u73af\u5883\u3002
    \u8fd9\u4e2a\u73b0\u8c61\u786e\u5b9e\u5728 linux \u4e0b\u53d1\u751f\u4e86\u3002\u6240\u4ee5\u767e\u601d\u4e0d\u5f97\u5176\u89e3\u3002
    \u8c22\u8c22\u56de\u590d\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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    \n
     \u8cc7\u6df1\u5927\u4f6c : Monad <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
     \"c++\u4e2d\u591a\u7ebf\u7a0b\u64cd\u4f5c 
     \"c++\u4e2d\u591a\u7ebf\u7a0b\u64cd\u4f5c 
    \u6211\u8fd9\u8fb9\u662f\u5728 operator=\u7684\u65f6\u5019\uff0cg++4.8.5                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : Monad <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Monad #14 \"c++\u4e2d\u591a\u7ebf\u7a0b\u64cd\u4f5c \u4e0d\u4e00\u5b9a\u4f1a\u5728\u8fd9\u91cc \u4e0a\u9762\u7684\u56fe\u4e0d\u5bf9 \u8865\u4e00\u4e2a\u56fe                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : hxndg <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 \u5efa\u8bae\u8fd8\u662f\u4e0a libc \u6e90\u7801\u770b\u770b\u5427\uff0c\u8fd9\u4e2a\u660e\u663e\u8ddf\u7f16\u8bd1\u5668\u884c\u4e3a\u6709\u5173\u4e86\u3002<\/p>\n
    \u4e0d\u8fc7\u6ca1\u660e\u767d\u5e72\u561b\u8981\u5e72\u8fd9\u79cd\u4e8b\u60c5\u5462\uff1f\u4e00\u822c\u8fd9\u79cd\u591a\u7ebf\u7a0b\u64cd\u4f5c\u90fd\u662f\u6781\u5ea6\u5c0f\u5fc3\u7684\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Monad \u4f1a\u6709\u4e24\u79cd core \u3002\u4e00\u79cd\u662f\u4f60\u5c1d\u8bd5\u7684\u8fd9\u4e2a\uff0c\u8fd8\u6709\u4e00\u79cd\u662f\u6211\u53d1\u7684\u90a3\u79cd\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u4e3b<\/span> \u8cc7\u6df1\u5927\u4f6c : blacksmith <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @hxndg \u7ebf\u4e0a\u7cfb\u7edf\u6709\u4e2a\u7c7b\u4f3c\u7684\u95ee\u9898\u88ab\u53d1\u73b0\u4e86\uff0c\u4e0d\u8fc7\u6808\u770b\u7740\u6bd4\u8f83\u5947\u602a\uff0c\u6211\u6309\u7167\u90a3\u4e2a\u903b\u8f91\u5199\u4e86\u8fd9\u4e2a\u6765\u590d\u73b0\u3002\u95ee\u9898\u5df2\u7ecf\u4fee\u590d\u4e86\uff0c\u4f46\u662f\u8fd8\u662f\u6ca1\u80fd\u627e\u5230\u4e00\u4e2a\u6bd4\u8f83\u4fe1\u670d\u7684\u89e3\u91ca\uff0c\u6765\u8bf4\u660e std::string key = local_name + “**”;\u8fd9\u884c\u4f1a core \u7684\u539f\u56e0\u3002
    \u786e\u5b9e\u591a\u7ebf\u7a0b\u64cd\u4f5c\u4e0d\u5c0f\u5fc3\u5bfc\u81f4\u7684\u95ee\u9898\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : matrixji <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @blacksmith \u91cd\u65b0\u770b\u4e86\u4e00\u4e0b libstdc++\u7684\u6e90\u7801\u3002baseic_string::operator=\u7684 \u5b9e\u73b0\uff0c\u4e0d\u540c\u7248\u672c\u4e0d\u4e00\u6837\u3002\u6240\u4ee5\u6211\u7684\u73af\u5883\u6c38\u8fdc\u4e0d\u4f1a codedump \u3002<\/p>\n
    https:\/\/github.com\/gcc-mirror\/gcc\/blob\/releases\/gcc-4.8.5\/libstdc%2B%2B-v3\/include\/bits\/basic_string.h \u662f Centos \u5bf9\u5e94\u7684\u7248\u672c\uff0c\u5b9e\u73b0\u5f88\u7b80\u5355\uff1a
    basic_string&
    operator=(const basic_string& __str) 
    { return this->assign(__str); }
    \u65e0\u6761\u4ef6\u5730\u53bb assign \u65b0\u7684\u5185\u5bb9\uff0cassign \u91cc\u9762\u7684\u903b\u8f91\u5c31\u662f free \u8001\u7684\uff0cclone \u65b0\u7684\u3002<\/p>\n
    https:\/\/github.com\/gcc-mirror\/gcc\/blob\/releases\/gcc-9.3.0\/libstdc++-v3\/include\/bits\/basic_string.h \u4f60\u53ef\u4ee5\u627e\u4e0b\u65b0\u7248\u7684\u5b9e\u73b0\u5c31\u4e0d\u4e00\u6837\u4e86\uff0c\u5982\u679c\u5f53\u524d\u7684\u957f\u5ea6\u591f\u4e86\uff0c\u5c31\u4e0d\u4f1a\u53bb free\uff0c\u800c\u662f\u76f4\u63a5\u5728\u5f53\u524d buffer \u4e0a Copy \u3002<\/p>\n
    \u7531\u4e8e\u662f\u591a\u7ebf\u7a0b\u64cd\u4f5c\uff0c\u6240\u4ee5\u4f1a\u9020\u6210\u4e24\u4e2a\u7ebf\u7a0b\u540c\u65f6\u6267\u884c assign \u7684\u64cd\u4f5c\u3002
    \u90a3\u4e48\u6709\u53ef\u80fd\u51fa\u73b0\uff1a
    \u540c\u4e00\u4e2a\u5730\u5740\u88ab free \u4e24\u6b21\uff0c\u7167\u6210 double free\uff0c\u90a3\u5c31\u662f @Monad \u63d0\u5230\u7684\u7b2c\u4e00\u4e2a\u9519\u8bef\u3002
    \u88ab free \u6389\u4e86\u7ee7\u7eed\u4f7f\u7528\uff0c\u90a3\u5c31\u662f\u4f60\u51fa\u73b0\u7684\u8fd9\u79cd\u60c5\u51b5\uff1a
     \u7ebf\u7a0b 1\uff1aFree -> New -> \u4f7f\u7528\uff08\u5b9e\u9645\u5df2\u7ecf\u88ab Free \u6389\u4e86\uff09
     \u7ebf\u7a0b 2\uff1a……………………..Free………….<\/p>\n
    \u6240\u4ee5 coredump \u7684\u65f6\u673a\u4e5f\u5c31\u4e0d\u4e00\u5b9a\u4e86\u3002\u5982\u679c\u4e3b\u8981\u7ec6\u7a76\uff0c\u53ef\u4ee5\u7528 valgrind \u8dd1\u4e00\u4e0b\u5c31\u6e05\u695a\u4e86\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : hxndg <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 local_name + “**”\u548c key \u5fc5\u7136\u662f\u653e\u5728\u6808\u4e0a\u7533\u8bf7\u7684\u4e34\u65f6\u53d8\u91cf\uff0c\u6309\u7167\u9053\u7406\u6765\u8bf4\u4e0d\u5e94\u8be5\u6709\u95ee\u9898\uff0c\u6240\u4ee5\u6211\u505a\u4e86\u4e2a\u5c1d\u8bd5\uff1a<\/p>\n
    \u6211\u628a\u4f60 B1.func1 \u6838 B2.func1 \u91cc\u9762\u7684`a->name = local_name`\u53bb\u6389\u4ee5\u540e\uff0c\u8bd5\u4e86\u4e0b\u5c31\u4e00\u76f4\u6ca1\u51fa\u73b0 core \u7684\u73b0\u8c61\u4e86\u3002<\/p>\n
    \u4f30\u8ba1\u53c8\u662f\u7f16\u8bd1\u5668\u505a\u7684\u4e00\u4e9b\u201c\u597d\u4e8b\u201d\u5bfc\u81f4\u7684\u95ee\u9898\uff0c\u611f\u89c9\u8fd8\u662f\u8ddf\u5229\u7528\u4e86 a->name \u6709\u5173\u7cfb\uff0c\u548c\u751f\u547d\u5468\u671f\u4ec0\u4e48\u7684\u6709\u5173\u3002<\/p>\n
    \u6211\u53f8\u4e4b\u6240\u4ee5\u4e0d\u7528 C++\uff0c\u7528 C \u4e00\u90e8\u5206\u539f\u56e0\u4e5f\u662f\u56e0\u4e3a\u907f\u514d\u7f16\u8bd1\u5668\u7684\u64cd\u4f5c\u3002\u3002\u3002\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
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     \u8cc7\u6df1\u5927\u4f6c : hxndg <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @matrixji 
    \u4e0d\uff0c\u4f60\u8fd9\u4e2a\u8bf4\u6cd5\u6ca1\u6709\u89e3\u91ca\u6e05\u695a\u4e3a\u4ec0\u4e48 local_name + “**”\u4e3a\u4ec0\u4e48\u4f1a core\uff0c
    \u6bcf\u4e2a\u7ebf\u7a0b\u90fd\u662f\u5728\u81ea\u5df1\u7684\u6808\u4e0a\u64cd\u4f5c\uff0clocal_name+”**”\u7684\u7ed3\u6784\u5e94\u8be5\u662f\u5728\u672c\u5730\u6808\u4e0a\u5206\u914d\u7684\uff0c\u5373\u4f7f assign \u7684\u662f\u76f4\u63a5\u8fd9\u4e2a\u5730\u5740\u4e5f\u4e0d\u5e94\u8be5 core \u624d\u5bf9\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : Wirbelwind <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @hxndg \u4e0a\u9762 a->name = local_name \u4e4b\u540e\uff0c\u7f16\u8bd1\u5668\u4e00\u5b9a\u7a0b\u5ea6\u4e0a\u53ef\u80fd\u4f1a\u76f4\u63a5\u4f7f\u7528\u4fdd\u5b58\u4e86 a->name \u7684\u5bc4\u5b58\u5668(\u5e94\u8be5\u662f a)\u6765\u66ff\u4ee3 local_name \u7684\u5bc4\u5b58\u5668                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n
    \n
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     \u8cc7\u6df1\u5927\u4f6c : hxndg <\/span>  <\/div>\n
     <\/i>            <\/span> <\/div>\n<\/p><\/div>\n
                                                                 @Wirbelwind \u55ef\uff0c\u6211\u4e5f\u6000\u7591\u662f\u8fd9\u4e2a\uff0c\u4f46\u662f\u6ca1\u628a\u4ee3\u7801\u4e0b\u4e0b\u6765\u770b\u5e76\u4e0d\u786e\u5b9a                                                            <\/div>\n<\/p><\/div>\n<\/li>\n
  • \n","protected":false},"excerpt":{"rendered":"
    c++\u4e2d\u591a\u7ebf\u7a0b\u64cd\u4f5c string …<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/325091"}],"collection":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=325091"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/325091\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=325091"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=325091"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=325091"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}