In this tutorial we will learn How to create a Simple Login Form in QT

File->New File or Project…

Applications->Qt Gui Application->Choose…

We keep the class as MainWindow as given by default.

Now We will create the second dialog by following step

Right Click Project -> New -> Qt -> Qt Designer Form class -> Choose -> Dialog without Button

Give the class name “SecDialog” and click finish.

LoginApp.pro

#-------------------------------------------------
#
# Project created by QtCreator 2016-04-18T22:31:03
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = LoginApp
TEMPLATE = app


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

HEADERS  += mainwindow.h \
    secdialog.h

FORMS    += mainwindow.ui \
    secdialog.ui

RESOURCES += \
    resource.qrc

Now we will design our mainwindow.ui file

Qt Login fom design

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.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "secdialog.h"
namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private slots:
    void on_pushButton_Login_clicked();

private:
    Ui::MainWindow *ui;
    SecDialog *secDialog;
};

#endif // MAINWINDOW_H

 

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QMessageBox>
#include <QPixmap>
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QPixmap pix(":/resources/img/login-icon.png");
    int w = ui->label_pic->width();
    int h = ui->label_pic->height();
    ui->label_pic->setPixmap(pix.scaled(w,h,Qt::KeepAspectRatio));

}

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

void MainWindow::on_pushButton_Login_clicked()
{
    QString username = ui->lineEdit_username->text();
    QString password = ui->lineEdit_password->text();

    if(username ==  "test" && password == "test") {
        QMessageBox::information(this, "Login", "Username and password is correct");
        //hide();
        secDialog = new SecDialog(this);
        secDialog->show();
    }
    else {
        QMessageBox::warning(this,"Login", "Username and password is not correct");
    }
}

 

secdialog.h

#ifndef SECDIALOG_H
#define SECDIALOG_H

#include <QDialog>

namespace Ui {
class SecDialog;
}

class SecDialog : public QDialog
{
    Q_OBJECT

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

private:
    Ui::SecDialog *ui;
};

#endif // SECDIALOG_H

 

secdialog.cpp

#include "secdialog.h"
#include "ui_secdialog.h"

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

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

 

resource.qrc

<RCC>
    <qresource prefix="/resources">
        <file>img/login-icon.png</file>
    </qresource>
</RCC>

 

Output