Linking error: undefined reference

**somedude** · 05-21-2009

Before you completely ignore this, I have read the dozens of other people posting this error and their solutions, but I have no idea how to fix this. Because some libraries were given to us, and cannot be modified, I'm finding it difficult to diagnose the problem. Yes this is for an assignment, but the closing stages of it.

I've attached the entire program, I'm a little desperate

Nothing malicious. When you unzip it, run make search in the dir.

The program should compile correctly, and then throws the linking error.

Big thanks in advance,
dude.

Parser.zip

**cyberfish** · 05-21-2009

Try adding

-L /path/to/the/directory/containing/the/library

to gcc/ld command.

[edit]
by the way, if you must attach files, use the attachment feature of the board. Chances are no one will go through all the hassle of downloading from rapidshare (all the countdowns and stuff) just to help you.
[/edit]

**somedude** · 05-21-2009

You aren't allowed to upload any sort of compressed file. But I'll upload it to another forum. One sec.

Also, there isn't anything wrong with my linking of the library, it knows where it is, it's just one linking error after everything else worked.

I will post the new download link in a minute.

**matsp** · 05-21-2009

And I suppose that if I try to do "make search", it probably won't compile on my Windows machine...

--
Mats

**hk_mp5kpdw** · 05-21-2009

Originally Posted by somedude

You aren't allowed to upload any sort of compressed file.

If you call it something.txt instead of something.zip then you can. Just let everybody know so they can rename the extension after downloading.

Also, what OS is this for, what IDE/compiler? And what specific linker error is it showing you?

**somedude** · 05-21-2009

Sorry yes, this is for unix machines, or those with access to unix via putty.

I've already uploaded to another forum.

Oh yeah...the only error I've yet to clean up is:

main.cc:(.text._ZN11NodeFactory14getNodeFactoryEv[NodeFactory::getNodeFactory()]+0x4): undefined reference to `NodeFactory::nodeFactory'

Okay, that specific error comes from the uni unix machines, compiled on terminal, running Red Hat, gcc-4.1.2.

ld: library not found for -lparser is the error I get on my Mac, gcc-4.0.2

**somedude** · 05-21-2009

I just realised that I omitted a .h file.

I've reuploaded the corrected one. Link above also corrected.

**matsp** · 05-21-2009

Do you actually have something in NodeFactory called nodeFactory?

--
Mats

**somedude** · 05-21-2009

Originally Posted by matsp

Do you actually have something in NodeFactory called nodeFactory?

--
Mats

Code:

class NodeFactory {
        // one will be needed so there is no point in deferring the creation
        // cf. Parser
        static NodeFactory nodeFactory;
protected:
        // hidden constructor so nothing can create a NodeFactory
        NodeFactory(void) { }
public:
        // this is the only means to get hold of the NodeFactory instance
        static NodeFactory *getNodeFactory(void) { return &nodeFactory; }

**matsp** · 05-21-2009

And I take it that you have declared your static variable somewhere else?

Remember, static variables in classes are just there to say "there is such a thing, somewhere". You then have to declare the type classname::variable somewhere in a .cpp file.

--
Mats

**somedude** · 05-21-2009

Originally Posted by matsp

And I take it that you have declared your static variable somewhere else?

Remember, static variables in classes are just there to say "there is such a thing, somewhere". You then have to declare the type classname::variable somewhere in a .cpp file.

--
Mats

I can't change these classes, given as part of the assignment. That is Parser.h, NodeFactory.h

Code:

class Parser {
	// although a Parser will be needed deferring the creation for illustrative purposes
	// cf. NodeFactory
	static Parser *parser;
	static NodeFactory *nodeFactory;
protected:
	// hidden constructor so nothing can create a Parser
	Parser(NodeFactory *nf) { nodeFactory = nf; };
public:
	// this is the only means to get hold of the Parser instance
	static Parser& getParser(NodeFactory *);

Other instances of NodeFactory:

Code:

#include "parser/Parser.h"
#include "subNode.h"

using namespace std;

int main() {
	Tokeniser tokeniser(cin);
	Parser & parser = Parser::getParser(NodeFactory::getNodeFactory());
	Node * query = parser.query(tokeniser);

	Context acontext;
	Hits result = (*query)(& acontext);
	cerr << * query << endl;
	return 0;
}

**brewbuck** · 05-21-2009

Originally Posted by somedude

I can't change these classes, given as part of the assignment. That is Parser.h, NodeFactory.h

You're screwed, then. The instructor should have provided an object file or library which contains the definition of that static member. You could define it yourself, but that's seriously improper.

**somedude** · 05-21-2009

Originally Posted by brewbuck

You're screwed, then. The instructor should have provided an object file or library which contains the definition of that static member. You could define it yourself, but that's seriously improper.

Stupid me. I misread the instructions. Two other directories aren't copied, parser is okay.

What do I need to change to fix this?

**brewbuck** · 05-21-2009

Originally Posted by somedude

Stupid me. I misread the instructions. Two other directories aren't copied, parser is okay.

What do I need to change to fix this?

Like I said, if this static member is part of a class that the instructor is providing, then there should be an object file (.obj or .o) or a lib file (.lib or .a) also provided with the headers, that defines the symbol.

The alternative is to define it yourself, in one of your source files:

Code:

NodeFactory NodeFactory::nodeFactory;

But this is conceptually WRONG, and will cause a linker error on the instructor's test system if he/she actually does provide this definition. You need to find out for sure.

**matsp** · 05-21-2009

You need to provide the static variable with a location, which you do by declaring a variable in some .cpp file for NodeFactory::nodeFactory; And you probably need the Parser:

arser and Parser::nodeFactory too.

--
Mats

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