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  1. #include<iostream>
  2. using std::cout;
  3. using std::endl;
  4.  
  5. class B;
  6. typedef void (*HANDLE_DOSOMETHING)(B *const, int q);
  7.  
  8. class B
  9. {
  10. public:
  11.   virtual void doSomething(int q)
  12.   {
  13.       std::cout<<"B::doSomething()"<<q<<endl;
  14.   }
  15.   void dummy()
  16.   {
  17.       HANDLE_DOSOMETHING *f1ptr = NULL;
  18.       int                *vtbl  = NULL;
  19.       int                *vptr  = (int *)this; // address of the object
  20.  
  21.       vtbl = (int *)*vptr; //address of the VTABLE
  22.  
  23.       f1ptr = (HANDLE_DOSOMETHING *)&(vtbl[0]); //address of the 1st virtual function
  24.       (*f1ptr)(this, 55);
  25.    }
  26. };
  27. int main()
  28. {
  29.     B objb;
  30.     objb.dummy();
  31.     return 0;  
  32. }
Success #stdin #stdout 0.01s 2724KB
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stdin
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Standard input is empty
stdout
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B::doSomething()55
https://ideone.com/lUhw58
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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