How to connect mainwindow and dialog using signal,slot

[toufic.dbouk]

void Dialog::seText(QString )
{
 
    ui->qwe->setText("qerr");
 
}

void Dialog::seText(QString )
{
 
    ui->qwe->setText("qerr");
 
}

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should be something like :

void Dialog::seText(QString str )
{
 
    ui->qwe->setText(str);
 
}

void Dialog::seText(QString str )
{
 
    ui->qwe->setText(str);
 
}

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try to avoid hard coding.

where are you doing this :

dialog=new Dialog; 
dialog->show();

dialog=new Dialog; 
dialog->show();

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show the function where this code executes , or show the complete code.