Sending QString value from one form class to another

[Kasun]

I have declared a QString in mainwindow.h as

public : QString str;

I have used the str inside a method of mainwindow.cpp and it now has a string value. I have another form named dialog.cpp I want to display the contents of str in a label named label1 in dialog.cpp!

Even though i imported mainwindow.h and mainwindow.cpp to dialog.cpp and used the following code to print the contents of str!

ui->label->setText(str);

It returns the error str as an undecalred identifier! How can i correct this?

[Pradeep Kumar]

HI,

have u declared str in dialog.cpp where u can show values to label,
and can u post the code of how u made a string value avialable in dialog.cpp from mainwindow.cpp.

Thanks,

[SGaist]

Hi and welcome to devnet,

Based on your question, you seem to be new to C++. I highly recommend that you start by reading a good book on the subject and then follow Qt's tutorial and examples.

Also, there are already a lot of similar questions on this forum. Did you try to search it first ?

[Kasun]

@Pradeep-Kumar

Dialog::Dialog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Dialog)
{
ui->setupUi(this);
MainWindow m;

ui->label->setText(str);

}

[Pradeep Kumar]

Hi,

u have not declared str, so the reason getting error.

Thanks,

[mrjj]

@Kasun
Hi, you create another instance of mainwindow.
Not sure that is what you want..
anyway, since str is inside the class, you must do

MainWindow m;
ui->label->setText(m.str);

But the m is not the running mainwindow. Its a new one.

[Kasun]

@mrjj I need from the old window! How can I do it?

[mrjj]

@Kasun

Often its easy to share from mainwindow since it opens the dialog

So if you add function to set the text to dialog.
public:
void Dialog::SetMyText(QString text) {
ui->label->setText(text);
}

Then in mainwin where u show dialog
void Mainwindow::ShowDia() {
Dialog dia;
dia.setMyText(str);
dia.exec();
}

[Amogh]

you can send the string to other class by simply placing it in the Signal, and catch the signal at the other class.