Question

I’m new to C++ and need some help with namespaces.
Following are my 4 files:

node.h <--class interface
node.cpp <--implementation
testNodeFunctions.cpp 
testNodeMain.cpp

//node.h
---------------------------------
#include <iostream>
using namespace std;

namespace namespaceName{

    class Node {
    private:
        int data;

    public:
        void setData( int x);
        int getData();

    };
   //and some more functions

}

//node.cpp
-------------------------------------
#include <iostream>
#include "node.h"
using namespace std;

namespace namespaceName {
      //provides implementation of the memeber functions
     int Node::getData() const{
       return data;
     }
     void Node::setData(int x){
     data=x;
     }

}//namespace


//testNodeFunctions.cpp 
-------------------------------------
#include <iostream>
#include "Node.h"
using namespace std;
using namespace namespaceName;

void showData(){
  //creates a Node object and prints some stuff
  Node a=37;
  cout<<a.getValue()<<endl;
}


//testNodeMain.cpp
----------------------------------------------
#include <iostream>
#include "Node.h"

void showData();

int main(){
//calls methods from testNodeFunctions
showData();
}

I’m not sure if I’m defining the namespace currently.

How Do I call the showData() function from the testNodeMain.cpp file. Currently I’m getting linker error stating that “undefined reference to namespaceName::Node::methodname”

Thanks so much in advance

Okay. That make sense. I removed , using namespace std from header. I’m compiling the testNodeMain.cpp which has the main(). the TestNodeMain.cpp calls functions from testNodeFunctions.cpp. testNodeFunctions.cpp creates Node object.

Answer 1

In your header file node.h, you have

    void setData( int x);
    int getData();

where as in your node.cpp file, you have:

 int Node::getValue() const{
   return data;
 }
 void Node::setValue(int x){
 data=x;
 }

You need to change your Node::getValue() const {} to Node::getData() const {}, or change the names of the functions in your header files to int getValue() and void setValue (int x)

The function names in the header files for the class and the actual .cpp file should be the same.