c++ recursive class

[npuleio]

Hello everyone!!!

I'd need a little hint on this little question:

I have a xml file I want to navigate and I have a library to process
it. But I want also to manage that file as an object to make clear and
efficient code.
So I coded two class which one is like recursive as like as in this
example:

class B : public xmlnode
{
public:
B(xmlnode* member);

LPCSTR getattribute(....);
void setattribute(....);

xmlnode* Node(LPCSTR nodename, LPCSTR attributenodename, LPCSTR
attributetosearch);

};

class A : public xmldocument
{
public:
A(LPCSTR xmlfilename);

xmlnode* Node(LPCSTR nodename, LPCSTR attributenodename,
LPCSTR attributetosearch);

};

So I can do this:

A* xmlobject = new A(filenamexmlblahblah);
xmlobject->Node(....,....,...)->Node(...,...,...)->GetAttribute(...);

where next nodes are nodes inside a parent node...but I get this link
error:

error LNK2019: unresolved external symbol "public: class B *
__thiscall B::Node(....)" ....

what I could have missed?...
Even I'm just using a function that returns class node itself....

Thanks to everyone!
Ciao
Luigi

[laserlight]

It looks like you just forgot to implement the B::Node member function.

By the way, please post your code in [code][/code] bbcode tags.

[npuleio]

Yes I just forgot to say I implemented in the CPP file:

xmlnode* xmlnode::Node(LPCSTR nodename,  LPCSTR attributenodename,
LPCSTR
attributetosearch)
{
....

}

but still I get that error

[laserlight]

That is the definition of xmlnode::Node, not B::Node.

[npuleio]

Ah sorry.... I typed wrong... I wanted to say in fact

class B : public xmlnode
{
public:
B(xmlnode* member);

LPCSTR getattribute(....);
void setattribute(....);

B* Node(LPCSTR nodename, LPCSTR attributenodename, LPCSTR
attributetosearch);

};

class A : public xmldocument
{
public:
A(LPCSTR xmlfilename);

B* Node(LPCSTR nodename, LPCSTR attributenodename,
LPCSTR attributetosearch);

};

B* B::Node(LPCSTR nodename,  LPCSTR attributenodename,
LPCSTR
attributetosearch)
{
....

}

and I get that error....

[laserlight]

Weird. I suggest that you reduce your program to the smallest and simplest program that demonstrates that error, then post the resultant program.

[npuleio]

Here the attachment for smallest and simplest demo application which at Button1 click should read the xml file and show in the edit box its value and instead I get this error:

1>prova_tinyxmlDlg.obj : error LNK2019: unresolved external symbol "public: char const * __thiscall documentTinyNode::GetAttribute(char const *)" (?GetAttribute@documentTinyNode@@QAEPBDPBD@Z) referenced in function "public: void __thiscall Cprova_tinyxmlDlg::OnBnClickedButton1(void)" (?OnBnClickedButton1@Cprova_tinyxmlDlg@@QAEXXZ)
1>prova_tinyxmlDlg.obj : error LNK2019: unresolved external symbol "public: class documentTinyNode * __thiscall documentTinyNode::Node(char const *,char const *,char const *)" (?Node@documentTinyNode@@QAEPAV1@PBD00@Z) referenced in function "public: void __thiscall Cprova_tinyxmlDlg::OnBnClickedButton1(void)" (?OnBnClickedButton1@Cprova_tinyxmlDlg@@QAEXXZ)
1>prova_tinyxmlDlg.obj : error LNK2019: unresolved external symbol "public: class documentTinyNode * __thiscall documentTinyXML::Node(char const *,char const *,char const *)" (?Node@documentTinyXML@@QAEPAVdocumentTinyNode@@PBD00@Z) referenced in function "public: void __thiscall Cprova_tinyxmlDlg::OnBnClickedButton1(void)" (?OnBnClickedButton1@Cprova_tinyxmlDlg@@QAEXXZ)
1>prova_tinyxmlDlg.obj : error LNK2019: unresolved external symbol "public: __thiscall documentTinyXML:ocumentTinyXML(char const *)" (??0documentTinyXML@@QAE@PBD@Z) referenced in function "public: void __thiscall Cprova_tinyxmlDlg::OnBnClickedButton1(void)" (?OnBnClickedButton1@Cprova_tinyxmlDlg@@QAEXXZ)
1>I:\projects\project_tests\prova_tinyxml\Debug\prova_tinyxml.exe : fatal error LNK1120: 4 unresolved externals

Any suggest?...

[pcuong1983]

Hi,
This error: "error LNK2019: unresolved external symbol .. " said
Linker could not find and definition of "documentTinyNode::GetAttribute" (for example)
Take note in your documentTinyNode class has only declaration of GetAttribute method.

and u must implement documentTinyNode::GetAttribute to resolve LNK2019 error

[npuleio]

Sorry I forgot something to attach in the package source... here the correct attachment test example... as you can see there are in the .cpp implementations of GetAttribute, SetAttribute and B:Node... but I still get that error...

Thanks
Ciao
Luigi

[pcuong1983]

Sorry I forgot something to attach in the package source... here the correct attachment test example... as you can see there are in the .cpp implementations of GetAttribute, SetAttribute and B:Node... but I still get that error...

Thanks
Ciao
Luigi

Your source code (prova_tinyxmlDlg.cpp) still missing implement documentTinyXML::Node(..)
Please complete implementation and rebuild your project

[npuleio]

Ehm... isn't implemented in prova_tinyxmlDlg.cpp almost at begin of the file?....

[npuleio]

Ah sorry.... now I understand... I shall implement also documentTinyXML::Node(..) when actually I implemented only documentTinyNode()...

I guess that member documentTinyXML::Node() should be implemented as like:

documentTinyNode* documentTinyXML::Node(LPCSTR nodename, ........ , ....... )
{
documentTinyNode::Node(nodename, ..... , ..... );
}

as an override of the documentTinyNode's function to get a node object... but those two classes aren't of same parent but just different objects... how it should be implemented then?...

Thanks
Ciao
Luigi

[pcuong1983]

Hi,
First of all, You should take a look at http://w3schools.com/xml/xml_tree.asp
"XML documents must contain a root element. This element is "the parent" of all other elements..."

As Xml document tree
the documentTinyXML class should be
class documentTinyXML
{
.....
public:
List<documentTinyNode> GetChildNodes(); // Return a collection of xmlNode
};

There is a good book Programming - Object-Oriented Analysis and Design - C++ to read
and your choose are yours

Merry Christmas !