mainwindow.obj:-1: error: LNK2019: unresolved external symbol "public: __thiscall MyForm::MyForm(class QWidge..........

[khalooei]

mainwindow.obj:-1: error: LNK2019: unresolved external symbol "public: __thiscall MyForm::MyForm(class QWidget *)" (??0MyForm@@QAE@PAVQWidget@@@Z) referenced in function "private: void __thiscall MainWindow::on_pushButton_clicked(void)" (?on_pushButton_clicked@MainWindow@@AAEXXZ)

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#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "myform.h"

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

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    MyForm *dialoge = new MyForm();
    dialoge->show();
}

[edit: Added missing codings tags SGaist]

[mcosta]

How is defined the Myform constructor?

Is MyForm defined in your .pro file?