[SOLVED] How to initialize ui in the function?

[kalster]

In my program, i have created a function. in that function is ui->textEdit->setText(totdMsg[totdNum]); which is crashing my program.
error: tipoftheday.cpp:22: warning: 'ui' is used uninitialized in this function. Can I have help in this please. How to initialize ui in the function?

when i replace Ui::TipOfTheDay *ui with Ui::TipOfTheDay *ui = new Ui::TipOfTheDay; then i do not get the warning message but my program still crashes.

Tipoftheday.cpp
@#include "tipoftheday.h"
#include "ui_tipoftheday.h"
#include "mainwindow.h"
#include <QDesktopWidget>
#include <QSettings>
#include <QCheckBox>

void DisplayTipOfTheDay();

TipOfTheDay::TipOfTheDay(QWidget *Child) :
QDialog(Child, Qt::CustomizeWindowHint |
Qt::WindowCloseButtonHint ),
ui(new Ui::TipOfTheDay)
{
ui->setupUi(this);
DisplayTipOfTheDay();

}

void DisplayTipOfTheDay(){
Ui::TipOfTheDay *ui;
ui->textEdit->setText(totdMsg[totdNum]);
}

TipOfTheDay::~TipOfTheDay()
{
delete ui;
}
@

tipoftheday.h
@#ifndef DIALOG_H
#define DIALOG_H

#include <QDialog>

namespace Ui {
class TipOfTheDay;
}

class TipOfTheDay : public QDialog
{
Q_OBJECT

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

private slots:

private:
Ui::TipOfTheDay *ui;

};

#endif // DIALOG_H@

[kalster]

I made some changes to the header file, removing the Ui::TipOfTheDay *ui;, but that only disabled the creation of widgets functions from within the cpp file. I really need some help in this topic.

[koahnig]

[quote author="kalster" date="1312774533"]
Tipoftheday.cpp
@
void DisplayTipOfTheDay(){
Ui::TipOfTheDay *ui;
ui->textEdit->setText(totdMsg[totdNum]);
}
@
[/quote]

That part does not look healthy at all.
You create the pointer, but how should the application know where it is pointing?

[kalster]

I finally solved it. i created a new function by adding TipOfTheDay:: to the function name that was giving me the error. Now i do not need that pointer in the function. here is my code...

tipoftheday.cpp
@void TipOfTheDay::DisplayTipOfTheDay()@

tipoftheday.h
@public:
void DisplayTipOfTheDay();@

the above two codes work nicely. The program runs fine now.

[aamer4yu]

Your problem was in line 21 of tipoftheday.cpp
You were declaring *ui locally. This local variable overrides the member variable visibility, and hence the error.

[kalster]

but i also declared it with the following code and my program still crashed but without the error message.

@Ui::TipOfTheDay *ui = new Ui::TipOfTheDay@

is this still declaring it locally. if so then what would be the alternative?

[aamer4yu]

You need not declare it locally. You have made it a member variable, remember ?
(tipoftheday.h line 22).

You just need to get rid of the line 21 in tipoftheday.cpp and rest should work fine.

[kalster]

if i removed line 21 from the cpp then i would get an error message error: 'ui' was not declared in this scope. line 22 in the header was declared as private and therefore i would need to declare it for the function.

create a new qt gui application and put the following into the mainwindow.cpp file and compile it. you will see the error that i am talking about.

@void test();
void test(){
ui->textEdit->setText("test");
}@

anyone know how to get this function to work?

[mlong]

[quote author="kalster" date="1312838955"]
create a new qt gui application and put the following into the mainwindow.cpp file and compile it. you will see the error that i am talking about.

@void test();
void test(){
ui->textEdit->setText("test");
}@

anyone know how to get this function to work?[/quote]

Make it MainWindow::test()

When you create a function outside the scope of the class (even if it lives in the class's .cpp or .h file), it cannot see the ui variable.

[kalster]

yes, in the scope is what i did in my third post. I guess in the scope is the only way. thank you mlong

[mlong]

No problem! There aren't really many reasons to have functions outside your class for this sort of thing. So, keeping them in scope is easy in that sense!

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