{"id":382695,"date":"2021-03-11T05:13:41","date_gmt":"2021-03-10T21:13:41","guid":{"rendered":"http:\/\/4563.org\/?p=382695"},"modified":"2021-03-11T05:13:41","modified_gmt":"2021-03-10T21:13:41","slug":"%e8%99%9a%e5%87%bd%e6%95%b0%ef%bc%8c%e8%99%9a%e8%a1%a8%e6%b7%b1%e5%ba%a6%e5%89%96%e6%9e%90","status":"publish","type":"post","link":"http:\/\/4563.org\/?p=382695","title":{"rendered":"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790"},"content":{"rendered":"<div>\n<div>\n<div>\n<h1>                  \u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790               <\/h1>\n<p> <\/p>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : yiouejv <\/span>  <span><i><\/i> 4<\/span> <\/div>\n<div> <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<\/p><\/div>\n<div isfirst=\"1\"> <\/p>\n<p>\u9762\u5411\u5bf9\u8c61\uff0c\u4ece\u5355\u4e00\u7684\u7c7b\u5f00\u59cb\u8bf4\u8d77\u3002<\/p>\n<pre><code>class A { private:     int m_a;     int m_b; }; <\/code><\/pre>\n<p>\u8fd9\u4e2a\u7c7b\u4e2d\u6709\u4e24\u4e2a\u6210\u5458\u53d8\u91cf\uff0c\u90fd\u662f<code>int<\/code>\u7c7b\u578b\uff0c\u6240\u4ee5\u8fd9\u4e2a\u7c7b\u5728\u5185\u5b58\u4e2d\u5360\u7528\u591a\u5927\u7684\u5185\u5b58\u7a7a\u95f4\u5462\uff1f<\/p>\n<p><code>sizeof(A)<\/code>, 8 \u4e2a\u5b57\u8282\uff0c\u4e00\u4e2a<code>int<\/code>\u5360\u7528\u56db\u4e2a\u5b57\u8282\u3002 \u4e0b\u56fe\u9a8c\u8bc1:<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a25fc5e81a.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/> <\/p>\n<p>\u8fd9\u4e24\u4e2a\u6570\u636e\u5728\u5185\u5b58\u4e2d\u662f\u600e\u6837\u6392\u5217\u7684\u5462\uff1f<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a2601a83cb.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/> <\/p>\n<p>\u539f\u6765\u662f\u8fd9\u6837\uff0c\u6211\u4eec\u6839\u636e debug \u51fa\u6765\u7684\u5730\u5740\u753b\u51fa a \u5bf9\u8c61\u5728\u5185\u5b58\u7684\u7ed3\u6784\u56fe<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a2605edf6b.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/>  <\/p>\n<p>\u5982\u679c <code>class A<\/code> \u4e2d\u5305\u542b\u6210\u5458\u51fd\u6570\u5462? A \u7684\u5927\u5c0f\u53c8\u662f\u591a\u5c11\uff1f<\/p>\n<pre><code>class A { public:     void func1() {}     private:     int m_a;     int m_b; }; <\/code><\/pre>\n<p>\u76f4\u63a5\u544a\u8bc9\u4f60\u7b54\u6848\uff0c\u7c7b\u7684\u6210\u5458\u51fd\u6570\u591a\u5927? \u6ca1\u4eba\u80fd\u56de\u7b54\u4f60\uff0c\u5e76\u4e14\u4e0d\u662f\u672c\u6587\u7684\u91cd\u70b9\uff0c\u7c7b\u7684\u6210\u5458\u51fd\u6570\u662f\u653e\u5728\u4ee3\u7801\u533a\u7684\uff0c\u4e0d\u7b97\u5728\u7c7b\u7684\u5927\u5c0f\u5185\u3002<\/p>\n<p>\u7c7b\u7684\u5bf9\u8c61\u5171\u4eab\u8fd9\u4e00\u6bb5\u4ee3\u7801\uff0c\u8bd5\u60f3\uff0c\u5982\u679c\u6bcf\u4e00\u4e2a\u5bf9\u8c61\u90fd\u6709\u4e00\u6bb5\u4ee3\u7801\uff0c\u5149\u662f\u5b58\u50a8\u8fd9\u4e9b\u4ee3\u7801\u5f97\u5360\u7528\u591a\u5c11\u7a7a\u95f4\uff1f \u6240\u4ee5\u540c\u4e00\u4e2a\u7c7b\u7684\u5bf9\u8c61\u5171\u7528\u4e00\u6bb5\u4ee3\u7801\u3002<\/p>\n<p>\u5171\u7528\u540c\u4e00\u6bb5\u4ee3\u7801\u600e\u4e48\u533a\u5206\u4e0d\u540c\u7684\u5bf9\u8c61\u5462\uff1f<\/p>\n<p>\u5b9e\u9645\u4e0a\uff0c\u4f60\u5728\u8c03\u7528\u6210\u5458\u51fd\u6570\u65f6\uff0c<code>a.func1()<\/code> \u4f1a\u88ab\u7f16\u8bd1\u5668\u7ffb\u8bd1\u4e3a <code>A::func1(&amp;a)<\/code>\uff0c\u4e5f\u5c31\u662f<code>A* const this<\/code>, this \u5c31\u662f a \u5bf9\u8c61\u7684\u5730\u5740\u3002<\/p>\n<p>\u6240\u4ee5\u6839\u636e this \u6307\u9488\u5c31\u80fd\u627e\u5230\u5bf9\u5e94\u7684\u6570\u636e\uff0c\u901a\u8fc7\u8fd9\u540c\u4e00\u6bb5\u4ee3\u7801\u6765\u5904\u7406\u4e0d\u540c\u7684\u6570\u636e\u3002<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a260b966a7.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/>  <\/p>\n<p>\u63a5\u4e0b\u6765\u6211\u4eec\u8ba8\u8bba\u4e00\u4e0b\u7ee7\u627f\uff0c\u5b50\u7c7b\u7ee7\u627f\u7236\u7c7b\uff0c\u5c06\u4f1a\u7ee7\u627f\u7236\u7c7b\u7684\u6570\u636e\uff0c\u4ee5\u53ca\u7236\u7c7b\u51fd\u6570\u7684\u8c03\u7528\u6743\u3002 <\/p>\n<p>\u4ee5\u4e0b\u7684\u6d4b\u8bd5\u53ef\u4ee5\u9a8c\u8bc1\u8fd9\u4e2a\u60c5\u51b5\u3002<\/p>\n<pre><code>class A { public:     void func1() { cout &lt;&lt; \"A func1\" &lt;&lt; endl; } private:     int m_a;     int m_b; };  class B : public A { public:     void func2() { cout &lt;&lt; \"B func2\" &lt;&lt; endl; } private:     int m_c; };  int main(int argc, char const* argv[]) {     B b;     b.func1();     b.func2();     return 0; } <\/code><\/pre>\n<p>\u8f93\u51fa:<\/p>\n<pre><code>\/\/ A func1 \/\/ B func2 <\/code><\/pre>\n<p>\u90a3\u4e48\u5bf9\u8c61 b \u5728\u5185\u5b58\u4e2d\u7684\u7ed3\u6784\u662f\u4ec0\u4e48\u6837\u7684\u5462\uff1f<\/p>\n<p>\u7ee7\u627f\u5173\u7cfb\uff0c\u5148\u628a a \u4e2d\u7684\u6570\u636e\u7ee7\u627f\u8fc7\u6765\uff0c\u518d\u6709\u4e00\u4efd\u81ea\u5df1\u7684\u6570\u636e\u3002<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a260fac3b8.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/>  <\/p>\n<p>\u6bcf\u4e2a\u5305\u542b\u865a\u51fd\u6570\u7684\u7c7b\u90fd\u6709\u4e00\u4e2a\u865a\u8868\uff0c\u865a\u8868\u662f\u5c5e\u4e8e\u7c7b\u7684\uff0c\u800c\u4e0d\u662f\u5c5e\u4e8e\u67d0\u4e2a\u5177\u4f53\u7684\u5bf9\u8c61\uff0c\u4e00\u4e2a\u7c7b\u53ea\u9700\u8981\u4e00\u4e2a\u865a\u8868\u5373\u53ef\u3002\u540c\u4e00\u4e2a\u7c7b\u7684\u6240\u6709\u5bf9\u8c61\u90fd\u4f7f\u7528\u540c\u4e00\u4e2a\u865a\u8868\u3002<\/p>\n<p>\u4e3a\u4e86\u6307\u5b9a\u5bf9\u8c61\u7684\u865a\u8868\uff0c\u5bf9\u8c61\u5185\u90e8\u5305\u542b\u6307\u5411\u4e00\u4e2a\u865a\u8868\u7684\u6307\u9488\uff0c\u6765\u6307\u5411\u81ea\u5df1\u6240\u4f7f\u7528\u7684\u865a\u8868\u3002\u4e3a\u4e86\u8ba9\u6bcf\u4e2a\u5305\u542b\u865a\u8868\u7684\u7c7b\u7684\u5bf9\u8c61\u90fd\u62e5\u6709\u4e00\u4e2a\u865a\u8868\u6307\u9488\uff0c\u7f16\u8bd1\u5668\u5728\u7c7b\u4e2d\u6dfb\u52a0\u4e86\u4e00\u4e2a\u6307\u9488\uff0c<code>*__vptr<\/code>\uff0c\u7528\u6765\u6307\u5411\u865a\u8868\u3002 \u8fd9\u6837\uff0c\u5f53\u7c7b\u7684\u5bf9\u8c61\u5728\u521b\u5efa\u65f6\u4fbf\u62e5\u6709\u4e86\u8fd9\u4e2a\u6307\u9488\uff0c\u4e14\u8fd9\u4e2a\u6307\u9488\u7684\u503c\u4f1a\u81ea\u52a8\u88ab\u8bbe\u7f6e\u4e3a\u6307\u5411\u7c7b\u7684\u865a\u8868\u3002<\/p>\n<pre><code>class A { public:     void func1() { cout &lt;&lt; \"A func1\" &lt;&lt; endl; }     virtual void vfunc1() { cout &lt;&lt; \"A vfunc1\" &lt;&lt; endl; } private:     int m_a;     int m_b; }; <\/code><\/pre>\n<p><code>cout &lt;&lt; sizeof(A);<\/code>, \u8f93\u51fa 12\uff0cA \u4e2d\u5305\u62ec\u4e24\u4e2a int \u578b\u7684\u6210\u5458\u53d8\u91cf\uff0c\u4e00\u4e2a\u865a\u6307\u9488\uff0c\u6307\u9488\u5360 4 \u4e2a\u5b57\u8282\u3002<\/p>\n<p>a \u7684\u5185\u5b58\u7ed3\u6784\u5982\u4e0b:<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a2613bfeb2.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/> <\/p>\n<p>\u865a\u8868\u662f\u4e00\u4e2a\u51fd\u6570\u6307\u9488\u6570\u7ec4\uff0c\u6570\u7ec4\u91cc\u5b58\u653e\u7684\u90fd\u662f\u51fd\u6570\u6307\u9488\uff0c\u6307\u5411\u865a\u51fd\u6570\u6240\u5728\u7684\u4f4d\u7f6e\u3002 <\/p>\n<p>\u5bf9\u8c61\u8c03\u7528\u865a\u51fd\u6570\u65f6\uff0c\u4f1a\u6839\u636e\u865a\u6307\u9488\u627e\u5230\u865a\u8868\u7684\u4f4d\u7f6e\uff0c\u518d\u6839\u636e\u865a\u51fd\u6570\u58f0\u660e\u7684\u987a\u5e8f\u627e\u5230\u865a\u51fd\u6570\u5728\u6570\u7ec4\u7684\u54ea\u4e2a\u4f4d\u7f6e\uff0c\u627e\u5230\u865a\u51fd\u6570\u7684\u5730\u5740\uff0c\u4ece\u800c\u8c03\u7528\u865a\u51fd\u6570\u3002<\/p>\n<p>\u8c03\u7528\u666e\u901a\u51fd\u6570\u5219\u4e0d\u50cf\u8fd9\u6837\uff0c\u666e\u901a\u51fd\u6570\u5728\u7f16\u8bd1\u9636\u6bb5\u5c31\u6307\u5b9a\u597d\u4e86\u51fd\u6570\u4f4d\u7f6e\uff0c\u76f4\u63a5\u8c03\u7528\u5373\u53ef\u3002<\/p>\n<pre><code>class A { public:     void func1() { cout &lt;&lt; \"A func1\" &lt;&lt; endl; }     virtual void vfunc1() { cout &lt;&lt; \"A vfunc1\" &lt;&lt; endl; } private:     int m_a;     int m_b; };  class B : public A { public:     void func1() { cout &lt;&lt; \"B func1\" &lt;&lt; endl; }     virtual void vfunc2() { cout &lt;&lt; \"B vfunc2\" &lt;&lt; endl; } private:     int m_a; }; <\/code><\/pre>\n<p>\u50cf\u8fd9\u6837\uff0cB \u7c7b\u7ee7\u627f\u81ea A \u7c7b\uff0cB \u4e2d\u53c8\u5b9a\u4e49\u4e86\u4e00\u4e2a\u865a\u51fd\u6570 vfunc2, \u5b83\u7684\u865a\u8868\u53c8\u662f\u600e\u4e48\u6837\u7684\u5462\uff1f<\/p>\n<p>\u7ed9\u51fa\u7ed3\u8bba\uff0c\u865a\u8868\u5982\u4e0b\u56fe\u6240\u793a:<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a261995b6c.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/> <\/p>\n<p>\u6211\u4eec\u6765\u9a8c\u8bc1\u4e00\u4e0b:<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a261e9d0e4.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/> <\/p>\n<pre><code>A a; B b; void(*avfunc1)() = (void(*)()) *(int*) (*(int*)&amp;a); void (*bvfunc1)() = (void(*)()) *(int*) *((int*)&amp;b); void (*bvfunc2)() = (void(*)()) * (int*)(*((int*)&amp;b) + 4); avfunc1(); bvfunc1(); bvfunc2(); <\/code><\/pre>\n<p>\u6765\u89e3\u91ca\u4e00\u4e0b\u4ee3\u7801: <code>void(*avfunc1)()<\/code> \u58f0\u660e\u4e00\u4e2a\u8fd4\u56de\u503c\u4e3a<code>void<\/code>, \u65e0\u53c2\u6570\u7684\u51fd\u6570\u6307\u9488 avfunc1, \u53d8\u91cf\u540d\u4ee3\u8868\u6211\u4eec\u60f3\u8981\u53d6 A \u7c7b\u7684 vfunc1 \u8fd9\u4e2a\u865a\u51fd\u6570\u3002<\/p>\n<p>\u53f3\u534a\u90e8\u5206\u7684\u7b2c\u4e00\u90e8\u5206\uff0c<code>(void(*)())<\/code> \u4ee3\u8868\u6211\u4eec\u6700\u540e\u8981\u8f6c\u6362\u6210\u5bf9\u5e94\u4e0a\u8ff0\u7c7b\u578b\u7684\u6307\u9488\uff0c\u53f3\u8fb9\u9700\u8981\u7ed9\u4e00\u4e2a\u5730\u5740\u3002<\/p>\n<p>\u6211\u4eec\u770b <code>(*int(*)&amp;a)<\/code>, \u628a a \u7684\u5730\u5740\u5f3a\u8f6c\u6210<code>int*<\/code>, \u518d\u89e3\u5f15\u7528\u5f97\u5230 \u865a\u6307\u9488\u7684\u5730\u5740\u3002<\/p>\n<p><code>*(int*) (*(int*)&amp;a)<\/code> \u518d\u5f3a\u8f6c\u89e3\u5f15\u7528\u5f97\u5230\u865a\u8868\u7684\u5730\u5740\uff0c\u6700\u540e\u5f3a\u8f6c\u6210\u51fd\u6570\u6307\u9488\u3002<\/p>\n<p>\u540c\u7406\u5f97\u5230 bvfunc1, bvfunc2, <code>+4<\/code>\u662f\u56e0\u4e3a\u4e00\u4e2a\u6307\u9488\u5360 4 \u4e2a\u5b57\u8282\uff0c<code>+4<\/code>\u5f97\u5230\u865a\u8868\u7684\u7b2c\u4e8c\u9879\u3002<\/p>\n<p><strong>\u8986\u76d6<\/strong><\/p>\n<pre><code>class A { public:     void func1() { cout &lt;&lt; \"A func1\" &lt;&lt; endl; }     virtual void vfunc1() { cout &lt;&lt; \"A vfunc1\" &lt;&lt; endl; } private:     int m_a;     int m_b; };  class B : public A { public:     void func1() { cout &lt;&lt; \"B func1\" &lt;&lt; endl; }     virtual void vfunc1() { cout &lt;&lt; \"B vfunc1\" &lt;&lt; endl; } private:     int m_a; }; <\/code><\/pre>\n<p>\u5b50\u7c7b\u91cd\u5199\u7236\u7c7b\u7684\u865a\u51fd\u6570\uff0c\u9700\u8981\u51fd\u6570\u7b7e\u540d\u4fdd\u6301\u4e00\u81f4\uff0c\u8be5\u79cd\u60c5\u51b5\u5728\u5185\u5b58\u4e2d\u7684\u7ed3\u6784\u4e3a:<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a2622e9b37.png\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/>  <\/p>\n<p><strong>\u591a\u6001<\/strong><\/p>\n<p>\u7236\u7c7b\u6307\u9488\u6307\u5411\u5b50\u7c7b\u5bf9\u8c61\u7684\u60c5\u51b5\u4e0b\uff0c\u5982\u679c\u6307\u9488\u8c03\u7528\u7684\u662f\u865a\u51fd\u6570\uff0c\u5219\u7f16\u8bd1\u5668\u4f1a\u5c06\u4f1a\u4ece\u865a\u6307\u9488\u6240\u6307\u7684\u865a\u51fd\u6570\u8868\u4e2d\u627e\u5230\u5bf9\u5e94\u7684\u5730\u5740\u6267\u884c\u76f8\u5e94\u7684\u51fd\u6570\u3002<\/p>\n<p>\u5b50\u7c7b\u5f88\u591a\u7684\u8bdd\uff0c\u6bcf\u4e2a\u5b50\u7c7b\u90fd\u8986\u76d6\u4e86\u5bf9\u5e94\u7684\u865a\u51fd\u6570\uff0c\u5219\u901a\u8fc7\u865a\u8868\u627e\u5230\u7684\u865a\u51fd\u6570\u6267\u884c\u540e\u4e0d\u5c31\u6267\u884c\u4e86\u4e0d\u540c\u7684\u4ee3\u7801\u561b\uff0c\u8868\u73b0\u51fa\u591a\u6001\u4e86\u561b\u3002<\/p>\n<p>\u6211\u4eec\u628a\u7ecf\u8fc7\u865a\u8868\u8c03\u7528\u865a\u51fd\u6570\u7684\u8fc7\u7a0b\u79f0\u4e3a\u52a8\u6001\u7ed1\u5b9a\uff0c\u5176\u8868\u73b0\u51fa\u6765\u7684\u73b0\u8c61\u79f0\u4e3a\u8fd0\u884c\u65f6\u591a\u6001\u3002\u52a8\u6001\u7ed1\u5b9a\u533a\u522b\u4e8e\u4f20\u7edf\u7684\u51fd\u6570\u8c03\u7528\uff0c\u4f20\u7edf\u7684\u51fd\u6570\u8c03\u7528\u6211\u4eec\u79f0\u4e4b\u4e3a\u9759\u6001\u7ed1\u5b9a\uff0c\u5373\u51fd\u6570\u7684\u8c03\u7528\u5728\u7f16\u8bd1\u9636\u6bb5\u5c31\u53ef\u4ee5\u786e\u5b9a\u4e0b\u6765\u4e86\u3002<\/p>\n<p>\u90a3\u4e48\uff0c\u4ec0\u4e48\u65f6\u5019\u4f1a\u6267\u884c\u51fd\u6570\u7684\u52a8\u6001\u7ed1\u5b9a\uff1f\u8fd9\u9700\u8981\u7b26\u5408\u4ee5\u4e0b\u4e09\u4e2a\u6761\u4ef6\u3002<\/p>\n<ul>\n<li>\u901a\u8fc7\u6307\u9488\u6765\u8c03\u7528\u51fd\u6570<\/li>\n<li>\u6307\u9488 upcast \u5411\u4e0a\u8f6c\u578b\uff08\u7ee7\u627f\u7c7b\u5411\u57fa\u7c7b\u7684\u8f6c\u6362\u79f0\u4e3a upcast \uff09<\/li>\n<li>\u8c03\u7528\u7684\u662f\u865a\u51fd\u6570<\/li>\n<\/ul>\n<p>\u4e3a\u4ec0\u4e48\u7236\u7c7b\u6307\u9488\u53ef\u4ee5\u6307\u5411\u5b50\u7c7b\uff1f<\/p>\n<p>\u5b50\u7c7b\u7ee7\u627f\u81ea\u7236\u7c7b\uff0c\u5b50\u7c7b\u4e5f\u5c5e\u4e8e A \u7684\u7c7b\u578b\u3002<\/p>\n<p>\u6700\u540e\u901a\u8fc7\u4e00\u4e2a\u4f8b\u5b50\u6765\u4f53\u4f1a\u4e00\u4e0b\u5427:<\/p>\n<pre><code>class Shape { public:     virtual void draw() = 0; };  class Rectangle : public Shape {     void draw() { cout &lt;&lt; \"rectangle\" &lt;&lt; endl; } };  class Circle : public Shape {     void draw() { cout &lt;&lt; \"circle\" &lt;&lt; endl; } };  class Triangle : public Shape {     void draw() { cout &lt;&lt; \"triangle\" &lt;&lt; endl; } };   int main(int argc, char const *argv[]) {     vector&lt;Shape*&gt; v;     v.push_back(new Rectangle());     v.push_back(new Circle());     v.push_back(new Triangle());     for (Shape* p : v) {         p-&gt;draw();     }     return 0; } <\/code><\/pre>\n<p>\u6709\u4e9b\u8bdd\u662f\u5927\u767d\u8bdd\uff0c\u54c8\u54c8\uff0c\u5982\u679c\u8fd9\u7bc7\u6587\u7ae0\u5199\u7684\u4e0d\u9519\uff0c\u89e3\u51b3\u4e86\u4f60\u7684\u7591\u60d1\u7684\u8bdd\uff0c\u70b9\u4e2a\u8d5e\u518d\u8d70\u5427\uff01<\/p>\n<p>\u4e0d\u5bf9\u7684\u5730\u65b9\u4e5f\u8bf7\u6307\u51fa\u6765\uff0c\u5927\u5bb6\u4e00\u8d77\u5b66\u4e60\u8fdb\u6b65\u3002<\/p>\n<p> <img decoding=\"async\" loading=\"lazy\" referrerpolicy=\"no-referrer\" rel=\"noreferrer\" src=\"http:\/\/4563.org\/wp-content\/uploads\/2021\/03\/20210311_604a2627363ea.gif\" alt=\"\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790\" \/>  <\/div>\n<div> <b>\u5927\u4f6c\u6709\u8a71\u8aaa<\/b> (<span>11<\/span>)        <\/div>\n<div> <\/div>\n<\/p><\/div>\n<\/p><\/div>\n<ul>\n<li data-pid=\"5395735\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : geelaw <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u6b63\u786e\u6807\u9898\uff1a\u6d45\u5ea6\u5256\u6790<\/p>\n<p>\u6df1\u5ea6\u5256\u6790\u81f3\u5c11\u5e94\u8be5\u6d89\u53ca\u591a\u91cd\u7ee7\u627f\u3001\u865a\u62df\u7ee7\u627f\u3001\u865a\u62df\u6790\u6784\u7684\u95ee\u9898\u3002                                                            <\/p><\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395736\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : jingous <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u611f\u89c9\u662f\u628a\u4faf\u6377\u8001\u5e08\u7684\u8bfe\u53c8\u590d\u8ff0\u4e86\u4e00\u904d                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395737\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : lqf96 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u8fd9\u2026\u8fde MSVC \u548c Itanium ABI \u4e0b\u865a\u8868\u7684\u7ed3\u6784\u548c\u533a\u522b\u90fd\u6ca1\u6709\u4e5f\u80fd\u53eb\u6df1\u5ea6                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395738\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : ArchScott <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u989d\uff0c\u73b0\u5728\u6821\u62db\u9762\u8bd5\u90fd\u4e0d\u6b62\u8bf4\u8fd9\u70b9\u5427&#8230;                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395739\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : yiouejv <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u8fd8\u6709\u8865\u5145\u7684\u53ef\u4ee5\u63a8\u8350\u4e00\u4e0b\u5417                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395740\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : Cyshall <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u8fd9\u79cd\u968f\u4fbf\u4e00\u641c\u5230\u5904\u90fd\u6709\u7684\u4e1c\u897f\u518d\u5199\u4e00\u904d\u771f\u7684\u53ea\u6709\u6d6a\u8d39\u65f6\u95f4\u8fd9\u4e00\u4e2a\u7528\u5904\u4e86\u3002                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395741\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : yiouejv <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @Cyshall \u6ca1\u6709\u81ea\u5df1\u6d4b\u4e00\u904d\u6df1\u523b\u7684\uff0c\u770b\u8fc7\u4e4b\u540e\uff0c\u771f\u7684\uff0c\u4e5f\u53ef\u4ee5\u6211\u6bd4\u8f83\u83dc\u54af                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395742\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : paoqi2048 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u53ef\u4ee5\uff0c\u6b63\u597d\u590d\u4e60\u4e00\u4e0b                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395743\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : ng29 <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u76f4\u63a5\u6c47\u7f16\u7801 \u5176\u5b9e\u66f4\u5bb9\u6613 \u6df1\u5ea6\u51fa\u6765\uff0c\u8fd8\u662f\u592a\u6d45\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395744\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u8cc7\u6df1\u5927\u4f6c : lraining <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             \u6df1\u5ea6\u63a2\u7d22 C++\u5bf9\u8c61\u6a21\u578b C++\u7f16\u8bd1\u5668\u5f00\u53d1\u8005\u5199\u7684\uff0c\u8bfb\u5b8c\u5c31\u4e0d\u4f1a\u5bf9\u9762\u5411\u5bf9\u8c61\u6709\u4ec0\u4e48\u7591\u95ee\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li data-pid=\"5395745\" data-uid=\"2\">\n<div>\n<div>\n<div> <span>\u4e3b<\/span> <span>\u8cc7\u6df1\u5927\u4f6c : yiouejv <\/span>  <\/div>\n<div> <i title=\"\u5f15\u7528\"><\/i>  <span>          <\/span> <\/div>\n<\/p><\/div>\n<div>                                                             @lraining \u8c22\u8c22\uff0c\u5df2\u7ecf\u5728\u8bfb\u4e86                                                            <\/div>\n<\/p><\/div>\n<\/li>\n<li>\n","protected":false},"excerpt":{"rendered":"<p>\u865a\u51fd\u6570\uff0c\u865a\u8868\u6df1\u5ea6\u5256\u6790 \u8cc7\u6df1\u5927\u4f6c :&hellip;<\/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\/382695"}],"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=382695"}],"version-history":[{"count":0,"href":"http:\/\/4563.org\/index.php?rest_route=\/wp\/v2\/posts\/382695\/revisions"}],"wp:attachment":[{"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=382695"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=382695"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/4563.org\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=382695"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}