Undefined reference to class::method

Question

In these days I thought I would try to work on some C++ Object Oriented Programming by converting one of my old programs to an object which methods I could use in other programs. The program is able to get an array of strings and print them to make a selection screen like this:

"> Stuff"
" Stuff2"
" Stuff3"

And the cursor could then be moved with the keyboard arrows and one entry could be selected by pressing Enter.
Unfortunately, after having removed most errors the only left is a "Undefined reference to class::method()" for each method that I wrote.
The code is the following:

Selection.cpp

#include "selection.h"
#include <iostream>
#include <conio.h>
#include <stdio.h>
#include <cstring>
#include <string>
#include <vector>
std::vector<entry> selectedArray;
int posizione = 1, tastoPremuto;    
void setCurrentArray(std::string selectionEntries[])
{
    //Copies a string array to a vector of struct entry
}

void resetSelection()
{
    //Blanks out every entry.segno
}

void selectionUpdate(int stato)
{
    //Moves the cursor
}

int getPosition()
{
    return posizione;  //Returns the position of the cursor
}

void setPosition(int nuovaPosizione)  //Sposta il puntatore alla nuovaPosizione
{
    posizione = nuovaPosizione;  //Sets the posiion of the cursor
}

entry getCurrentEntry(int posizioneCorrente)  //Returna l'entry della posizione attuale
{
    //Gets the name of the entry at which the cursor is
}

void printEntries()  //Stampa tutte le entries con la selezione
{
    //Prints all the entries with the cursor before them
}

int getSelection(bool needConfirm)
{
    //gets the selection from keyboard
}

Selection.h

#ifndef SELECTION_H
#define SELECTION_H
#include <string>
#include <vector>

struct entry
{
    std::string entryName;
    char sign;
};

class selection
{
   public:
    selection();
    virtual ~selection();
    void setCurrentArray(std::string selectionEntries[]);
    void resetSelection();
    int getPosition();
    void setPosition(int nuovaPosizione);
    entry getCurrentEntry(int posizioneCorrente);
    void printEntries(int argumentsNumber);
    int getSelection(bool needConfirm);
protected:
private:
    int tastoPremuto;
    int posizione;
    void selectionUpdate(bool stato);
    std::vector<entry> selectedArray;
};

#endif // SELECTION_H

main.cpp

#include <stdio.h>
#include <iostream>
#include <conio.h>
#include <selection.h>
#include <vector>
#include <array>

std::string selezioneTestArray[3] = {"Prima selezione", "Seconda selezione", "Terza seleazione"};

int main()
{
    selection sel;
    sel.setCurrentArray(selezioneTestArray);
    sel.setPosition(0);
    sel.resetSelection();
    sel.printEntries(3);
    sel.getSelection(true);
    return 0;
}

If you need the whole code, it's in my Github: https://github.com/LiceoFederici2H/Vita-Da-Lavoratore
Sorry if it's in Italian but I meant to use this also as a school project.
Thanks in advance.

score 1 · Accepted Answer · answered May 11 '14 at 14:57

1

In source file (Selection.cpp), you have to qualify the method names with class name:

void Selection::setCurrentArray(std::string selectionEntries[])
{
  //Copies a string array to a vector of struct entry
}

Otherwise these methods will be free function, and not definition of the class methods. As a result, your class methods remain undefined, and when linker tries to link with the methods, it can not find them, and shows undefined reference of the method error.

answered May 11 '14 at 14:57

Rakib

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Thanks, now it works. It crashes on startup, though. Any idea about why it does that? – Kien Tuong Truong May 11 '14 at 15:02
1

@user3624242: That's either a separate question, or something that needs to be added to your main question, I think. – Rook May 11 '14 at 15:03
@user3624242, I recommend reading [How to Debug Small Programs](http://ericlippert.com/2014/03/05/how-to-debug-small-programs/) to get a better idea of how to debug this. – chris May 11 '14 at 15:03
@user3624242, you should post separate question with relevant code where it crashes. – Rakib May 11 '14 at 15:04

Undefined reference to class::method

1 Answers1