When the button is pressed, it doesn't copy the LineEdit in Label.

[Cleofas]

My_Window::My_Window(QWidget *parent) : QWidget(parent)
{
QPushButton *set_text_button=new QPushButton(this);
QLabel *text_label=new QLabel(this);
QLineEdit *line_edit=new QLineEdit(this);
QHBoxLayout *main_layout=new QHBoxLayout(this);
set_text_button->setText("Set Text");
text_label->setText("0");
line_edit->setText("0");
main_layout->addWidget(set_text_button);
main_layout->addWidget(line_edit);
main_layout->addWidget(text_label);
temp_text=line_edit->text();
QObject::connect(set_text_button,SIGNAL(clicked(bool)),this,SLOT(slot_send_text()));
QObject::connect(this,SIGNAL(signal_send_text(QString)),text_label,SLOT(setText(QString)));
setWindowTitle("Changing text on label");
}
void My_Window::slot_send_text()
{
emit (signal_send_text(temp_text));
}

When the button is pressed, the label-a text should be the same as the lineedit-a text, but somehow it doesn't happen.

[Demir]

Where's your elephant? slot_send_text() Is the variable temp_text? Try to rewrite the slot as follows:

emit (signal_send_text(line_edit->text()));

Or so (may be clearer):

temp_text = line_edit->text();
emit (signal_send_text(temp_text));