Comparing QString causes the program to crash .

[ladiesfinger]

Hi all ,
i designed a form using Qt designer and compiled it with uic to produce
ui_mainwindow.h
The other files are :
1. main.cpp
2. mainwindow.cpp
3. mainwindow.ui
4. mainwindow.h ( default files )

i've included ui_mainwindow file in header file.
In my form , among many other fields , i want to get username and password from QLineEdit .
When the user press login pushbutton , it should check the name and password manually entered in the corresponding slot invoked .
here's the slot's func:

void MainWindow::on_login_clicked()
{
user=usernameip->displayText();        // usernameip is lineedit's name 
pass=passwordip->displayText();       //         ''                ''
    if(user.compare("user")&&pass.compare("pass"))
    {
        //i wanted to invoke another dialog from here but i cant put even a msgbox
        //'coz the program crashes bfore entering this
    }

void MainWindow::on_login_clicked()
{
user=usernameip->displayText();        // usernameip is lineedit's name 
pass=passwordip->displayText();       //         ''                ''
    if(user.compare("user")&&pass.compare("pass"))
    {
        //i wanted to invoke another dialog from here but i cant put even a msgbox
        //'coz the program crashes bfore entering this
    }

To copy to clipboard, switch view to plain text mode 

Both user and pass are declared as QString in header file.
If u need the code for other files , ill post it immediately .
i spent about some 3 hours without success , this is my first prog ...

[tbscope]

I have a feeling it might not have to do with the QString.
Are you using an uninitialised pointer?

[ladiesfinger]

tbscope , i checked that but i didn't initialise any of the UI items manually.i left what uic generated . Is that necessary to initialise them ?

here's the code ....they're simple .
mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QMessageBox>
#include "ui_mainwindow.h"
 
namespace Ui {
    class MainWindow;
    class Ui_MainWindow;
}
 
class MainWindow : public QMainWindow ,public Ui_MainWindow
{
    Q_OBJECT
public:
    QString user;
    QString pass;
    QMessageBox msg;
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private:
    Ui::MainWindow *ui;
private slots:
    void on_login_clicked();
};
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QMessageBox>
#include "ui_mainwindow.h"

namespace Ui {
    class MainWindow;
    class Ui_MainWindow;
}

class MainWindow : public QMainWindow ,public Ui_MainWindow
{
    Q_OBJECT
public:
    QString user;
    QString pass;
    QMessageBox msg;
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private:
    Ui::MainWindow *ui;
private slots:
    void on_login_clicked();
};
#endif // MAINWINDOW_H

To copy to clipboard, switch view to plain text mode 

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::on_login_clicked()
{
user=usernameip->displayText();
pass=passwordip->displayText();
    if(user.compare("user")&&pass.compare("pass"))
    {
        //msg.setText("The username is correct");
        //msg.exec();
    }
}

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

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::on_login_clicked()
{
user=usernameip->displayText();
pass=passwordip->displayText();
    if(user.compare("user")&&pass.compare("pass"))
    {
        //msg.setText("The username is correct");
        //msg.exec();
    }
}

To copy to clipboard, switch view to plain text mode 

And the uic generated file ui_mainwindow.h file
Does anyone has idea wat's wrong ?

[tbscope]

I guess it should be

ui->usernameip

ui->usernameip

To copy to clipboard, switch view to plain text mode 

But that does not explain why it crashed. It shouldn't even compile.

[ladiesfinger]

thnk u tbscope ,but i reallly didn't understand that.
The program compiled and ran.
Only wen i click the login button ,i says " windows app stopped working".
here's the screenshots as attachments .

The error statement :
Starting C:\Users\Administrator\Documents\Qt Pros\TravelBooking-build-desktop\debug\TravelBooking.exe...
Error - RtlWerpReportException failed with status code :-1073741823. Will try to launch the process directly
RtlWerpReportException failed with status code :-1073741823. Will try to launch the process directly

[tbscope]

That's an error completely unrelated to the code you posted.

[wysota]

As a side note (completely unrelated to the problem) - I think you are not using "layouts" in your code which makes your GUI look and act really bad (sorry for being blunt).

[ladiesfinger]

That's an error completely unrelated to the code you posted

tbscope , I've posted all the files ! . I think i should write a new one step by step carefully.

hi wysota , you mean i've to write the code without the help of designer ?
Does designing & then using uic tool is a bad advice ? I thought writing manually will take lots of time .

[wysota]

hi wysota , you mean i've to write the code without the help of designer ?

No. I mean you need to organize widgets in layouts. Also see conept of layouts in Designer docs.

[ladiesfinger]

Thank u all guys for ur instant help especially tbscope .