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c++intelicc

Where does Intel C++ Compiler store the vptr ( pointer to virtual function table ) in an Object?

Where does Intel C++ Compiler store the vptr ( pointer to virtual function table ) in an Object ?

I believe MSVC puts it at the beginning of the object, gcc at the end. What is it for icpc ( Intel C++ Compiler )?

Solution

  • For Intel C++ compiler, for Linux, I found it to be the beginning of the object.

    Code:

    #include <cstdio>

class A 
{
  int a, b;
public:
  A(int a1, int b1): a(a1), b(b1) {}
  virtual void p(void) { printf("A\n"); }
};

class B: public A
{
public:
  B(int a1, int b1): A(a1, b1) {}
  void p(void){ printf("B\n"); }
};

int main(void)
{
  A a(1, 2); int p=10; A a1(5, 6);
  B b(3, 4); int q=11; B b2(7, 8);

  a.p();
  b.p();

  int * x=(int*)&a;
  printf("%d %d %d %d\n", x[0], x[1], x[2], x[3]);
  x=(int*)&b;
  printf("%d %d %d %d\n", x[0], x[1], x[2], x[3]);
}