How to solve the multiple definition in Qt? - c++

Question

I don´t know why I got this problem, the header files are just included once but it continuous showing the error, I also already check the .pro file and every SOURCE is just included once. How can I solve this?
I will attach the files I'm using and their include and the code of the little ones
globals.h
#ifndef GLOBALS_H
#define GLOBALS_H
#include <QtGlobal>
#include "structs.h"
QT_BEGIN_NAMESPACE
struct ListaPaquetes;
QT_END_NAMESPACE
extern ListaPaquetes *nuevoPaquete;
#endif // GLOBALS_H
mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QtGui>
#include <QDialog>
#include <QtCore>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_startButton_clicked();
void on_planificarProduButton_clicked();
private:
Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H
produccion.h (only the first lines)
#ifndef PRODUCCION_H
#define PRODUCCION_H
#include <QDialog>
structs.h (onyl first lines)
Here is the struct ListaPaquetes, which is the responsible of the error, so the problem I guess is with this file but I don't know why
#ifndef STRUCT_H
#define STRUCT_H
#include <QString>
#include <QList>
struct Nodo
{
int cantidad;
QString tipoPaquete;
Nodo *siguiente;
Nodo *anterior;
Nodo(){}
Nodo (int cant, QString paquete)
{
cantidad = cant;
tipoPaquete = paquete;
siguiente = nullptr;
anterior = nullptr;
}
};
struct ListaPaquetes
{
Nodo *pn;
ListaPaquetes()
{
pn = nullptr;
}
void crearPaquete(int,QString);
QList<QString> paquetesAgregados();
};
void ListaPaquetes::crearPaquete(int cant, QString paquete)
{
if (pn==nullptr)
{
pn = new Nodo(cant, paquete);
pn->siguiente = pn;
pn->anterior = pn;
}
else
{
Nodo *nuevo = new Nodo(cant, paquete);
pn->anterior->siguiente=nuevo;
nuevo->anterior = pn->anterior;
nuevo->siguiente=pn;
pn->anterior = nuevo;
}
}
QList<QString> ListaPaquetes::paquetesAgregados()
{
QList <QString> paquetes;
if (pn!=nullptr)
{
Nodo *tmp = pn;
do
{
paquetes.append(tmp->tipoPaquete);
tmp = tmp->siguiente;
}while(tmp!=pn);
}
return paquetes;
}
#endif // STRUCT_H
globals.cpp
#include "globals.h"
ListaPaquetes *nuevoPaquete = new ListaPaquetes();
main.cpp
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
mainwindow.cpp
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QColor>
#include <QColormap>
#include <QtCore>
#include <QtGui>
#include <QMessageBox>
#include "produccion.h"
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
void MainWindow::on_startButton_clicked()
{
if(ui->cantGalletas->text() == "")
{
QMessageBox::warning(this,"Error","Debe introducir una cantidad de
galletas");
}
}
void MainWindow::on_planificarProduButton_clicked()
{
Produccion *ventanaPaquetes = new Produccion();
ventanaPaquetes->show();
}
produccion.cpp (When I run something from here, it shows the error)
#include "produccion.h"
#include "ui_produccion.h"
#include <QtCore>
#include <QMessageBox>
#include "globals.h"
Here are the errors:

Answer 1

You are getting the problem because you are putting the implementation of member functions in header files (here structs.h). Every source file that includes globals.h will include structs.h and compile the functions implemented there. When you link your program these functions are multiply defined
You need to move ListaPaquetes::crearPaquete(int cant, QString paquete) and
ListaPaquetes::crearPaquete(int cant, QString paquete) into structs.cpp