C++的虚表到底是怎么玩的?求指教

OwnWaterloo

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2. $ g++ -fdump-class-hierarchy
   

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http://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
-fdump-class-hierarchy (C++ only)
-fdump-class-hierarchy-options (C++ only)
    Dump a representation of each class's hierarchy and virtual function table layout to a file. The file name is made by appending .class to the source file name, and the file is created in the same directory as the output file. If the ‘-options’ form is used, options controls the details of the dump as described for the -fdump-tree options.

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2. $ cl /d1reportAllClassLayout
   

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http://connect.microsoft.com/Vis ... ject-layout-browser

...
In the mean time, you can use the undocumented (and unsupported) compiler switches /d1reportSingleClassLayout<class> and /d1reportAllClassLayout to get the information you want from your build. For more information on these switches, please read Andy's excellent blog post: http://blogs.msdn.com/vcblog/arc ... fixing-lnk2022.aspx

Peter-Michael Osera
Visual C++ Compiler Team

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2. $ clang -cc1 --help | grep layouts
   
3.   -fdump-record-layouts   Dump record layout information
   
4.   -fdump-vtable-layouts   Dump the layouts of all vtables that will be emitted in a translation unit
   

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建议将代码改成这样再去试：

1. 
   
2. class ca { public: virtual ~ca() {} };
   
3. class cb { public: virtual ~cb() {} };
   
4. class cc : public ca, public cb { public: virtual ~cc() {} };
   
5. class cd: public cc { public: virtual ~cd() {} };
   
6. 
   
7. int main(int argc, char* argv[])
   
8. {
   
9.       switch (argc)
   
10.       {
    
11.       default: return 0;
    
12.       case 1: return sizeof(ca);
    
13.       case 2: return sizeof(cb);
    
14.       case 3: return sizeof(cc);
    
15.       case 4: return sizeof(cd);
    
16.       }
    
17. }
    

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OwnWaterloo

回复 3# _BlueGuy__

我不做游戏、不谈哲学、不玩Lua、不写web服务器、不用学也没什么机会用C/C++。外带也不乱搞男女关系。
即使加进去过不了一周就会屏蔽群消息 —— 群里至少有3位能作证我这不是在乱说。
所以还是算了吧。啊。