Qt creator fails to create header files for UI's (Dialogs)

rhonaldjr

Hi,

In my Desktop Application, I have created a dialog UI through the IDE (derived from QDialog).

DlgLogin, derived from QDialog

I can find the UI, .cpp and .h added to the project file (below).

SOURCES += main.cpp\
        mainwindow.cpp \
    dlglogin.cpp

HEADERS  += mainwindow.h \
    dlglogin.h

FORMS    += mainwindow.ui \
    dlglogin.ui

When I compile, there is no issue. But when I refer the dialog file like the below, the program doesn't run.

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include "dlglogin.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    DlgLogin login;
    login.setModal(true);
    login.show();

    ui->setupUi(this);
}

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

it gives the below errors.

*mainwindow.obj:-1: error: LNK2019: unresolved external symbol "public: __cdecl DlgLogin::DlgLogin(class QWidget *)" (??0DlgLogin@@QEAA@PEAVQWidget@@@Z) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget *)" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
mainwindow.obj:-1: error: LNK2019: unresolved external symbol "public: virtual __cdecl DlgLogin::~DlgLogin(void)" (??1DlgLogin@@UEAA@XZ) referenced in function "public: __cdecl MainWindow::MainWindow(class QWidget )" (??0MainWindow@@QEAA@PEAVQWidget@@@Z)
debug\Akounts.exe:-1: error: LNK1120: 2 unresolved externals

When I add include "ui_dlglogin.h" in the header, it gives the below error message.
XXX\mainwindow.cpp:3: error: C1083:Cannot open include file: 'ui_dlglogin.h': No such file or directory

My build directory is outside the project folder and I cannot find ui_dlglogin.h file inside. I can understand that the UI compiler is not able to generate the source code and hence the linker is throwing this error message. How do I resolve this? I have gone through the responses in most of the forums and it didn't work.

I am currently working on Windows 10 machine with Qt Creator 4.2.1, MSVC 2015 32-Bit compiler (my machine is 64 bit and I am using 64 bit Qt)

dheerendra

Can you check which directory the ui_dlglogin.h file exist ? Does it exist in some directory ?

mrjj

Can you show your constructor of the dialog
It looks for
DlgLogin::DlgLogin(class QWidget *)

So does the destructor have default == NULL ?

rhonaldjr

@dheerendra I didn't find ui_dlglogin.h anywhere. The build directory is outside the project directory and I didn't find it there. However, I can find ui_mainwindow.h there

Eddy

Hi,

Sometimes if you make important changes to a project it is a good thing to uses 'Clean' + 'Qmake' + rebuild.
This might help the linker finding what it needs.

Eddy

rhonaldjr

@mrjj my dlglogin.h source code

#ifndef DLGLOGIN_H
#define DLGLOGIN_H

#include <QDialog>

namespace Ui {
class DlgLogin;
}

class DlgLogin : public QDialog
{
    Q_OBJECT

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

private:
    Ui::DlgLogin *ui;
};

#endif // DLGLOGIN_H

my dlglogin.cpp source code

#include "dlglogin.h"
#include "ui_dlglogin.h"

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

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

rhonaldjr

@Eddy thanks. This one helped. after 4 hours, I saw my program run :-)

Eddy

Glad you can move on!

We all have been in the same situation like you had just now. ;-)
Every time I see linker errors like this I clean my project as described.

Could you please mark the topic as solved.

rhonaldjr

@Eddy thanks a lot. I thought I had marked as solved. Let me check

Pradeep Kumar

@rhonaldjr

u have marked as solved.
cheers.

Thanks,