undefined reference to a defined function in c++?

Question

Im very new to c++, so I will need some help for this. Here is the code:

RootNode.h

#ifndef ROOTNODE_H
#define ROOTNODE_H


class RootNode
{
    public:

        int getNodeId();
        void setNodeId(int i );

    protected:
    private:
        int node_id;
};

#endif // ROOTNODE_H

RootNode.cpp

class RootNode{
    private:
        int node_id;

RootNode()
{
    //ctor
    this->setNodeId(0);
}

void setNodeId(int i ){
    node_id = i;
}

int getNodeId(){
    return node_id;
}

~RootNode()
{
    //dtor
}

};

main.cpp

#include <stdio.h>
#include <iostream>
#include "LeafNode.h"
#include "DecisionNode.h"
#include "RootNode.h"
using namespace std;


int main(int argc, const char* argv[]){
        RootNode rootNode;
        cout<<rootNode.getNodeId();




return 0;
};

I get this error when I try to compile with g++:

$ g++ RootNode.cpp main.cpp
/tmp/ccylUcLS.o: In function `main':
main.cpp:(.text+0x17): undefined reference to `RootNode::getNodeId()'
collect2: error: ld returned 1 exit status

I have looked online, but I really dont understand what goes wrong. I have also tried to build with CodeBlocks, but its of no use.

Thank you!

Khalil Khalaf · Accepted Answer · 2016-04-25 23:24:45Z

3

Your .cpp file should look something like this:

#include "RootNode.h"

int RootNode::getNodeId()
{
// stuff
}

void RootNode::setNodeId(int i)
{
// stuff
}

edited Apr 25, 2016 at 23:24

answered Apr 25, 2016 at 23:23

Khalil Khalaf

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4 Comments

kfsone Over a year ago

And it should probably #include rootnode.h shouldn't it?

Khalil Khalaf Over a year ago

Definitely. I will add it

kfsone Over a year ago

You don't need the class RootNode definition now - that's coming from RootNode.h

MingiuX Over a year ago

And remember that if you want to define custom constructor and destructor you have to insert prototypes in your class definition in RootNode.h

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