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While coding an algorithm for the following problem, there are a few
compilation errors that I don't completely understand. The errors
are:-

error C2839: invalid return type 'Human **' for overloaded 'operator -
>'

error C2039: 'PrintFamilyTree' : is not a member of
'std::_Vector_iterator<_Ty,_Alloc>'
1> with
1> [
1> _Ty=Human *,
1> _Alloc=std::allocator<Human *>
1> ]

I think C2839 probably triggers C2039, however I'm unable to pinpoint
the problem.

Here's the code and solution.
-----------------------------------------------------------------------------------------------------------
Implement method PrintFamilyTree() that prints out the Name and
Generation of the tree.

Output should resemble
Name: Jan Generation:0
Name: Mike Generation:1
Name: Greg Generation:2
Name: Carol: Generation: 2
Name: Peter Generation: 3
Name: Marcia Generation: 3
Name: Bobby Generation: 1


class Human : public std::vector<Human *>
{
public:
Human(const std::string &name) : m_Name(name) {};
virtual void PrintFamilyTree(const short &generation = 0) const;
protected:
std::string m_Name;
};

class Male: public Human
{
public:
Male(const std::string &name) : Human(name) {};
};

class Female: public Human
{
public:
Female(const std::string &name) : Human(name) {};
};

void main()
{
Male m1("Mike"), m2("Greg"), m3("Peter"), m4("Bobby");
Female f1("Carol"), f2("Marcia"), f3("Jan");
m1.push_back(&m2);
f1.push_back(&m3);
f1.push_back(&f2);
m1.push_back(&f1);
f3.push_back(&m1);
f3.push_back(&m4);
f3.PrintFamilyTree();
}

Solution
------------

void PrintFamilyTree(const short& generation)
{
printf("Name : %s Generation = %d\n", m_Name.c_str(),generation);
vector<Human*>::iterator it;
for (it = this.begin(); it< this.end() ;it++)
{
it->PrintFamilyTree(generation+1);
}
}

-----------------------------------------------------------------------------------------------------------
The problem occurs at the line:-
it->PrintFamilyTree(generation+1);

Ankur Arora wrote:
> While coding an algorithm for the following problem, there are a few
> compilation errors that I don't completely understand. The errors
> are:-
>
> error C2839: invalid return type 'Human **' for overloaded 'operator -
>> '
>
> error C2039: 'PrintFamilyTree' : is not a member of
> 'std::_Vector_iterator<_Ty,_Alloc>'
> 1> with
> 1> [
> 1> _Ty=Human *,
> 1> _Alloc=std::allocator<Human *>
> 1> ]
> [..]
>
> void PrintFamilyTree(const short& generation)
> {
> printf("Name : %s Generation = %d\n", m_Name.c_str(),generation);
> vector<Human*>::iterator it;
> for (it = this.begin(); it< this.end() ;it++)

What's "this" doing here? As I understand the language rules, the line
above should not compile. Or is that function inside a class
definition? Then it still not supposed to compile since 'this' is a
pointer and with a pointer '.' cannot be used (pointers don't have members).

Also, it is more idiomatic to use != when comparing an iterator to the
end of the container being iterated, not <.

> {
> it->PrintFamilyTree(generation+1);
> }
> }
>
> -----------------------------------------------------------------------------------------------------------
> The problem occurs at the line:-
> it->PrintFamilyTree(generation+1);

Are you sure?

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

* Ankur Arora:
> While coding an algorithm for the following problem, there are a few
> compilation errors that I don't completely understand. The errors
> are:-
>
> error C2839: invalid return type 'Human **' for overloaded 'operator -
>> '
>
> error C2039: 'PrintFamilyTree' : is not a member of
> 'std::_Vector_iterator<_Ty,_Alloc>'
> 1> with
> 1> [
> 1> _Ty=Human *,
> 1> _Alloc=std::allocator<Human *>
> 1> ]
>
> I think C2839 probably triggers C2039, however I'm unable to pinpoint
> the problem.
>
> Here's the code and solution.
> -----------------------------------------------------------------------------------------------------------
> Implement method PrintFamilyTree() that prints out the Name and
> Generation of the tree.
>
> Output should resemble
> Name: Jan Generation:0
> Name: Mike Generation:1
> Name: Greg Generation:2
> Name: Carol: Generation: 2
> Name: Peter Generation: 3
> Name: Marcia Generation: 3
> Name: Bobby Generation: 1
>
>
> class Human : public std::vector<Human *>
> {
> public:
> Human(const std::string &name) : m_Name(name) {};
> virtual void PrintFamilyTree(const short &generation = 0) const;
> protected:
> std::string m_Name;
> };
>
> class Male: public Human
> {
> public:
> Male(const std::string &name) : Human(name) {};
> };
>
> class Female: public Human
> {
> public:
> Female(const std::string &name) : Human(name) {};
> };
>
> void main()

Your instructor or book should not teach you such bad habits.

'void' is not permitted as result type of 'main'.

Not in C, not in C++.

Use 'int main'.


> {
> Male m1("Mike"), m2("Greg"), m3("Peter"), m4("Bobby");
> Female f1("Carol"), f2("Marcia"), f3("Jan");
> m1.push_back(&m2);
> f1.push_back(&m3);
> f1.push_back(&f2);
> m1.push_back(&f1);
> f3.push_back(&m1);
> f3.push_back(&m4);
> f3.PrintFamilyTree();
> }
>
> Solution
> ------------
>
> void PrintFamilyTree(const short& generation)

This does not match the declaration in the class. Worse, you're not definining
the class' member routine but some free-standing routine.

To get going on this, replace above with

void Human:rintFamilyTree(const short& generation) const

The logic below is sound, i.e. it'll work, but the coding is ungood.

You'll get a host of compilation errors. Just fix them one by one.


> {
> printf("Name : %s Generation = %d\n", m_Name.c_str(),generation);
> vector<Human*>::iterator it;
> for (it = this.begin(); it< this.end() ;it++)
> {
> it->PrintFamilyTree(generation+1);
> }
> }


Cheers & hth.,

- Alf

On Dec 2, 10:14*am, Victor Bazarov <v.Abaza...@comAcast.net> wrote:
> Ankur Arora wrote:
> > While coding an algorithm for the following problem, there are a few
> > compilation errors that I don't completely understand. The errors
> > are:-
>
> > error C2839: invalid return type 'Human **' for overloaded 'operator -
> >> '
>
> > error C2039: 'PrintFamilyTree' : is not a member of
> > 'std::_Vector_iterator<_Ty,_Alloc>'
> > 1> * * * *with
> > 1> * * * *[
> > 1> * * * * * *_Ty=Human *,
> > 1> * * * * * *_Alloc=std::allocator<Human *>
> > 1> * * * *]
> > [..]
>
> > void PrintFamilyTree(const short& generation)
> > {
> > * printf("Name : %s Generation = %d\n", m_Name.c_str(),generation);
> > * vector<Human*>::iterator it;
> > * for (it = this.begin(); it< this.end() ;it++)
>
> What's "this" doing here? *As I understand the language rules, the line
> above should not compile. *Or is that function inside a class
> definition? *Then it still not supposed to compile since 'this' is a
> pointer and with a pointer '.' cannot be used (pointers don't have members).
>
> Also, it is more idiomatic to use != when comparing an iterator to the
> end of the container being iterated, not <.
>
> > * {
> > * * *it->PrintFamilyTree(generation+1);
> > * }
> > }
>
> > -----------------------------------------------------------------------------------------------------------
> > The problem occurs at the line:-
> > it->PrintFamilyTree(generation+1);
>
> Are you sure?
>
> V
> --
> Please remove capital 'A's when replying by e-mail
> I do not respond to top-posted replies, please don't ask

Oh. Sorry for pasting the wrong code.
Yes 'PrintFamilyTree' is a member function and I'm using 'this->' as
against 'this.'.
Yes those are the line which the compiler is reporting errors on.
But I suspect that the line

for (it = this->begin(); it< this->end() ;it++)

is probably where the errors are originating from.
From looking at the class hierarchy (i.e. how its derived from
std::vector<Human*>, do you think this is the right way to iterate
over the elements?

Ankur Arora wrote:
> Oh. Sorry for pasting the wrong code.
> Yes 'PrintFamilyTree' is a member function and I'm using 'this->' as
> against 'this.'.
> Yes those are the line which the compiler is reporting errors on.
> But I suspect that the line
>
> for (it = this->begin(); it< this->end() ;it++)
>
> is probably where the errors are originating from.
> From looking at the class hierarchy (i.e. how its derived from
> std::vector<Human*>, do you think this is the right way to iterate
> over the elements?

It's the right way. The only problem is that when you dereference 'it',
the resulting value is still a pointer (since 'this' is a vector of
pointers to Human). So you need two indirections here:

(*it)->PrintFamilyTree(generation+1);

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask