Question on C++ parent and child functions

[Eric]

Consider the following:

class ParentClass
{
public:
void FunctionOne( void );
protected:
void FunctionTwo( void );
private:
void FunctionThree( void );
};


ParentClass::FunctionOne( void )
{
FunctionTwo();
}

ParentClass::FunctionTwo( void )
{
FunctionThree();
}

ParentClass::FunctionThree( void )
{
printf( "Executing parent class's FunctionThree\n" );
}


class ChildClass : public ParentClass
{
public:
void FunctionTwo( void );
void FunctionThree( void );
};

ChildClass::FunctionTwo( void )
{
FunctionThree();
}

ChildClass::FunctionThree( void )
{
printf( "Executing child class's FunctionThree\n" );
}

int main( int argc, char** argv )
{
ChildClass* ccPtr = new ChildClass;

ccPtr->FunctionOne();
}


There is no ChildClass::FunctionOne(), so it's actually
ParentClass::FunctionOne() that gets executed.

My question is, is the call to FunctionTwo() within FunctionOne() a
call to the parent class's FunctionTwo(), or the child class's
FunctionTwo()?

I suspect it's the former (parent class), so my question then becomes,
how do I force it to execute the child class's FunctionTwo()?

Maybe something like pass FunctionOne() the "this" pointer and then
have FunctionOne call FunctionTwo and FunctionThree using the this
pointer (i.e. "CallersThis->FunctionOne()" and
"CallersThis->FunctionTwo()")?

 

[Pete C]

My question is, is the call to FunctionTwo() within FunctionOne() a
call to the parent class's FunctionTwo(), or the child class's
FunctionTwo()?

I suspect it's the former (parent class), so my question then becomes,
how do I force it to execute the child class's FunctionTwo()?

You are correct - it executes the parent's FunctionTwo because
FunctionTwo is not virtual. Declare FuntionTwo and FunctionThree as
virtual (in the parent class, and optionally in the derived class) and
you'll see the behaviour you want.