C++ class with multiple constructors - Header and cpp file

Question

I have a C++ class where I have two constructors. In the file minhaclasse. h:

public:
  MinhaClasse(int x1);
  MinhaClasse(int x1, int x2);

Then in the.cpp file I create normally the constructors I declared there in the header. So far so good. The problem now happens in my Main class. In the header file of the Main class, I want to declare inside public:

public:
  MinhaClasse classe;

But if I run the project at this point, the line above gives error, saying that there is an ambiguity, because as I did not initialize the class object, and it does not know which constructor to use. The only way I did and it worked was not declare the object inside the Header, and leave to declare it whole already inside the CPP:

 MinhaClasse classe = MinhaClasse(5);

So I come to my question: whether the class MinhaClasse has two builders, has some "trick" for, in my class Main, can declare the 'class' object inside the Header, without initializing it, or in this case I will need to really not create the header object and leave to declare it completely inside the CPP??

File calculator. h

#ifndef CALCULADORA_H
#define CALCULADORA_H
class Calculadora
{
public:
    Calculadora(int x=0);
    Calculadora(int x=0, int y=0);
};
#endif // CALCULADORA_H

File calculator.cpp:

#include "calculadora.h"
#include "qdebug.h"
Calculadora::Calculadora(int x)
{
    qDebug() << x;
}
Calculadora::Calculadora(int x, int y)
{
    qDebug() << x+y;
}

And on the mainwindow. h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "calculadora.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:

private:
    Ui::MainWindow *ui;
    Calculadora calc; // aqui dá o erro!!!!
};

#endif // MAINWINDOW_H

Answer 1

Instead of "run" the class call directly with:

private:
    Ui::MainWindow *ui;
    Calculadora calc; // aqui dá o erro!!!!

Do so:

private:
    Ui::MainWindow *ui;
    Calculadora *calc;

And on CPP call it that:

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    calc = new Calculadora();
}

Read more on:

• What is the use of pointers?

Error call of overloaded is ambiguous

What happens is that when you try to set default parameters it cannot decide which one to use.

Instead:

public:
    Calculadora(int x=0);
    Calculadora(int x=0, int y=0);

Do this:

public:
    Calculadora(int x=0);
    Calculadora(int x, int y);