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Displaying vtable when debugging

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4.89/5 (9 votes)
30 Jun 2010CPOL 35.5K   10   3
This tip show how to display all entries from a C++ vtable in the VS debugger.
Due to some limitations the virtual table of an object is not shown by default in the debugger. In some cases only the entries from the base class is shown.

class Base
{
    virtual void a();
};
class Derived : public Base
{
    virtual void b();
};
Base* ptr = new Derived();


which in a watch window gives
ptr->__vfptr	0x004420f8 const Derived::`vftable'
	[0x0]	0x00415ed3 Base::a(void)



You can look at the entire vtable if you add this helper variable:

void (**vt)() = *(void (***)())ptr;


and then inspect vt,X in a watch window, where X is the number of expected virtual function entries.

vt,2 gives in the example above
vt,2	0x004420f8 const Derived::`vftable'
  [0x0]	0x00415ed3 Base::a(void)
  [0x1]	0x00415ee2 Derived::b(void)


Idea originates from here[^], and it's too good to not share.

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

 
QuestionHelper variable not needed! Pin
Stefan_Lang16-Jul-13 22:59
Stefan_Lang16-Jul-13 22:59 
GeneralReason for my vote of 5 Thanks Niklas Pin
RioWing23-Dec-11 6:30
RioWing23-Dec-11 6:30 
GeneralReason for my vote of 5 Very neat! Pin
Harrison H26-Oct-10 9:43
Harrison H26-Oct-10 9:43 

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