'Mainmenu' does not name a type - c++

Question

I'm working on car sharing project. So, I've done login and registration, after login the main menu is opening. In main menu I need to output a balance of an account. I do like this:
mainwindow.h
#include <QMainWindow>
#include <QMessageBox>
#include <string>
#include <QDebug>
#include "mainmenu.h"
using namespace std;
class RegData;
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
RegData& givedata(); // the object of class from which I will get balance and output it in main menu
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
private slots:
void on_button_reg_clicked();
void on_button_log_clicked();
private:
Ui::MainWindow *ui;
Mainmenu *second; // the error is in this line
};
class RegData
{
private:
QString login;
QString email;
QString password;
int balance;
public:
RegData(QString log = "", QString mail = "", QString pass = "", int bal=0) : login(log), email(mail), password(pass), balance(bal)
{
}
void output()
{
qDebug() << login<<email<<password<<balance;
}
QString getLogin()
{
return login;
}
QString getEmail()
{
return email;
}
QString getPassword()
{
return password;
}
int getBalance()
{
return balance;
}
void setLogin(QString log)
{
login = log;
}
void setEmail(QString mail)
{
email = mail;
}
void setPassword(QString pass)
{
password = pass;
}
void setBalance(int balanc)
{
balance = balanc;
}
};
Ok, how I did registration:
Receiving data from file into QVector data;
Receiving data from login/pass lines etc.
If login hasn't registered yet, put the data into file
So, there are a part of code in login system. The part checks is account registered, if it is, do something. In my case I change 'givedata()' values
for(QVector<RegData>::iterator it = data.begin(); it<data.end(); it++)
{
if(loginline == it->getLogin() && passwordline == it->getPassword() || loginline == it->getEmail() && passwordline == it->getPassword())
{
islog = true;
givedata().setLogin(loginline);
givedata().setEmail(it->getEmail());
givedata().setPassword(passwordline);
givedata().setBalance(it->getBalance());
break;
}
else
{
islog = false;
}
}
but I have an error
C:\Users\david\Documents\Carsharring_files\mainwindow.h:33: ошибка: 'Mainmenu' does not name a type
Mainmenu *second;
^
What is the line for? This is for main menu window object
I need to do some things with 'givedata()' in another window, there is why I do it
mainmenu.h is included
#ifndef MAINMENU_H
#define MAINMENU_H
#include <QDialog>
#include <QMessageBox>
#include "addmoney.h"
#include "mainwindow.h"
namespace Ui {
class Mainmenu;
}
class Mainmenu : public QDialog
{
Q_OBJECT
public:
explicit Mainmenu(QWidget *parent = 0);
~Mainmenu();
private slots:
void on_plus_clicked();
private:
Ui::Mainmenu *ui;
};
#endif // MAINMENU_H
I changed nothing in mainmenu.h, but includes

Answer 1

You have a cyclic dependency of header files.
mainmenu,h includes mainwindow.h
mainwindow.h includes mainmenu.h
That's trouble (and note that couldn't be determined without seeing both header files).