I want to write a code that increases the value in the line edit when the checkbox is clicked.

[wtimm]

@JonB we have defined the variable val in the above answers (the value in the line edit)

Can we do it if we define val inside the setValue function or should we do it using another function?

void Widget::on_grabDataButton_clicked()
{
QSettings settings;
settings.setValue("val",1);
settings.value("val").toInt();
}

[Pl45m4]

@wtimm said in I want to write a code that increases the value in the line edit when the checkbox is clicked.:

void Widget::on_grabDataButton_clicked()
{
QSettings settings;
settings.setValue("val",1);
settings.value("val").toInt();
}

Dont know what this should do. Maybe you are using QSettings wrong.

To set value
settings.setValue("val", 42);

To read the value:
int val = settings.value("val").toInt();

And do whatever you like with val (set it to your line edit after you start your program)

[wtimm]

@JonB can you take a look at the code i wrote, where is my mistake ?

[Pl45m4]

@wtimm

The mistake is that it seems that you are not doing something with your value. It makes no sense to write and read the setting at the same place of your code (every time you click a button). Read it, where you need the value.

[wtimm]

@Pl45m4

void Widget::on_grabDataButton_clicked()
{
}

void Widget::on_mt_IncreaseValueButton_clicked()
{
auto originalLength = ui->mt_SerialNumberLineEdit->text().length();
auto val = ui->mt_SerialNumberLineEdit->text().toInt();
val += ui->mt_SpinBox->value();
ui->mt_SerialNumberLineEdit->setText(QString::number(val));
ui->mt_SerialNumberLineEdit->setText(QString::number(val).rightJustified(originalLength , '0'));
}
QSettings settings;
settings.setValue("val",42);
settings.value("val").toInt();

where should i use code in

[Pl45m4]

@wtimm said in I want to write a code that increases the value in the line edit when the checkbox is clicked.:

where should i use code in

Not in your buttonClicked handlers.

You save the current value one time, when you close your program and read it one time to write it back to your lineEdit, when you start your program.

e.g. your D'tor to save your value (obviously before you destroy your GUI) and maybe showEvent() to read your settings.

[JonB]

@JonB said in I want to write a code that increases the value in the line edit when the checkbox is clicked.:

When I save the increased value, how can I make the increased value show as default when I open the project again?

Read it back in somewhere at startup and set the widget's value from the previously saved.

[SGaist]

Hi,

@wtimm said in I want to write a code that increases the value in the line edit when the checkbox is clicked.:

settings.value("val").toInt();

What exactly do you think that line is doing ?
How can it change anything with regards to your widgets ?

[wtimm]

i don't quite understand how can i do this

[SGaist]

As others have already written:

• read the settings into a variable
• do any computation you might need (it might be none)
• set the result on the widget that is supposed to contain it

[wtimm]

I can't code it

[JonB]

@wtimm
What about Googling for, say, QSettings examples? For example, the wiki's How to Use QSettings looks like it has an example like yours?

[wtimm]

i searched and tried but i can't code it

[SGaist]

You do realize that between the wiki page @JonB linked to that is doing what you and the "restoring the state of a GUI application" example of the QSettings class, you have everything you need to write that part for your application ?

[wtimm]

void Widget::on_mt_IncreaseValueButton_clicked()
{
auto originalLength = ui->mt_SerialNumberLineEdit->text().length();
auto val = ui->mt_SerialNumberLineEdit->text().toInt();
val += ui->mt_SpinBox->value();
ui->mt_SerialNumberLineEdit->setText(QString::number(val));
ui->mt_SerialNumberLineEdit->setText(QString::number(val).rightJustified(originalLength , '0'));
}

How can I print and read the val variable here in the file ? I also want it to overwrite the value continuously.

[wtimm]

bool WriteFile(){

QFile file("mt_SerialNumber.txt");

QTextStream stream(&file);
while(val != NULL)
{
    stream << QString::number(val);
}

return true;

}

I defined something like this to main.cpp, but it says undeclared identifier because I can't pull val

[Pl45m4]

@wtimm

Do you even read what we write?

I defined something like this to main.cpp, but it says undeclared identifier because I can't pull val

Because you probably dont have val in your main.cpp. Return it there from your object instance of your widget.

[wtimm]

i tried to return but i got a error message like void function should not return a value

[mrjj]

@wtimm
that means you have something like

void func() {
return 20;
}

so you need to change the return type unless its a slot as then it wont work as you think.

[JonB]

@wtimm
I do not mean to be unkind, but do you not think you should read some books or tutorials about C++ programming? From your problems you need to understand some of the basics, your questions are not really about Qt.